scholarly journals Interactions between Biotite and the Mineral-Weathering Bacterium Pseudomonas azotoformans F77

2020 ◽  
Vol 86 (7) ◽  
Author(s):  
Yuan-Li Wang ◽  
Li-Jing Sun ◽  
Chun-Mei Xian ◽  
Feng-Lian Kou ◽  
Ying Zhu ◽  
...  
Keyword(s):  
Gluconic Acid ◽  
Direct Contact ◽  
Molecular Mechanisms ◽  
Acid Metabolism ◽  
Cell Attachment ◽  
Mineral Weathering ◽  
Flow Area ◽  
Content Type ◽  
Silicate Minerals ◽  
Expression Levels

ABSTRACT In this study, the mineral-weathering bacterium Pseudomonas azotoformans F77, which was isolated from the soil of a debris flow area, was evaluated for its weathering activity under direct contact with biotite or without contact. Then, biotite-weathering behaviors of strain F77, mutants that had been created by deleting the gcd and adh genes (which are involved in gluconic acid metabolism and pilus formation, respectively), and the double mutant F77ΔgcdΔadh were compared. The relative gene expression levels of F77 and its mutants F77Δgcd and F77Δadh were also analyzed in the presence of biotite. Direct contact with biotite increased Fe and Al release from the mineral in the presence of F77. All strains had similar abilities to release Fe and Al from the mineral except for F77Δgcd and F77Δadh. Mobilized Fe and Al concentrations were decreased by up to 72, 26, and 87% in the presence of F77Δgcd, F77Δadh, and F77ΔgcdΔadh, respectively, compared to levels observed in the presence of F77 during the mineral-weathering process. Gluconic acid production was decreased for F77Δgcd and F77ΔgcdΔadh, while decreased cell attachment on the mineral surface was observed for F77Δadh, compared to findings for F77. The F77 genes involved in pilus formation and gluconic acid metabolism showed increased expression levels in the presence of biotite. The results of this study showed important roles for the genes involved in gluconic acid metabolism and pilus formation in mineral weathering by F77 and demonstrated the distinctive effect of these genes on mineral weathering by F77. IMPORTANCE Bacteria play important roles in mineral weathering and soil formation, although the molecular mechanisms underlying the interactions between bacteria and silicate minerals are poorly understood. In this study, the interactions between biotite and the highly effective mineral-weathering bacterium P. azotoformans F77 were characterized. Our results showed that the genes involved in gluconic acid metabolism and pilus formation play important roles in mineral weathering by F77. The presence of biotite could promote the expression of these genes in F77, and a distinctive effect of these genes on mineral weathering by F77 was observed in this study. Our results provide new knowledge and promote better understanding regarding the interaction between silicate minerals and mineral-weathering bacteria, as well as the molecular mechanisms involved in these processes.

A Combination of Genomics, Transcriptomics, and Genetics Provides Insights into the Mineral Weathering Phenotype of Pseudomonas azotoformans F77

2021 ◽  
Author(s):  
Yuan-Li Wang ◽  
Wen Dong ◽  
Kai-Xiang Xiang ◽  
Qi Wang ◽  
Lin-Yan He ◽  
...  
Keyword(s):  
Metabolic Pathways ◽  
Gluconic Acid ◽  
Acid Production ◽  
Molecular Mechanisms ◽  
Acid Metabolism ◽  
Reducing Power ◽  
Acid Tolerance ◽  
Mineral Weathering ◽  
Silicate Mineral ◽  
Flagellar Assembly

Silicate mineral weathering (dissolution) plays important roles in soil formation and global biogeochemical cycling. In this study, a combination of genomics, transcriptomics, and genetics was used to identify the molecular basis of mineral weathering activity and acid tolerance in Pseudomonas azotoformans F77. Biotite was chosen as a silicate mineral to investigate mineral weathering. The genome of strain F77 was sequenced, and the genes significantly upregulated when grown in the presence of biotite included mineral weathering-related genes associated with gluconic acid metabolism, flagellar assembly, and pilus biosynthesis and acid tolerance-related genes associated with neutralizing component production, reducing power, and proton efflux. Then, the biotite-weathering behaviors of strain F77 and its mutants that were created by deleting the tkt , tal , gntP , potF , nuoF , and gdtO genes, which are involved in gluconic acid metabolism and acid tolerance, respectively, were determined. The Fe and Al concentrations in the strain F77-inoculated medium increased 2.2- to 13.7-fold compared to the controls. The cell numbers of strain F77 increased over time, while the pH values in the medium ranged from 3.75 to 3.90 between 20 and 36 h of incubation. The release of Al and Fe was significantly reduced in the mutants F77Δ tal , F77Δ gntP , F77Δ potF , and F77Δ nuoF . Bacterial growth was significantly reduced in the presence of biotite in the mutants F77Δ potF and F77Δ nuoF . Our results demonstrated the acid tolerance of strain F77 and suggested that multiple genes and metabolic pathways in strain F77 are involved in biotite weathering and acid tolerance during the mineral weathering process. IMPORTANCE Acid production and tolerance play important roles in effective and persistent mineral weathering in bacteria, although the molecular mechanisms governing acid production and acid tolerance in bacteria have not been fully elucidated. In this study, the molecular mechanisms underlying biotite (as a silicate mineral) weathering (dissolution) and acid tolerance of P. azotoformans F77 were characterized using genomics, transcriptomics, and genetics analyses. Our results showed that the genes and metabolic pathways for gluconic acid metabolism, flagellar assembly, and pilus biosynthesis may play important roles in mineral weathering by strain F77. Notably, the genes associated with neutralizing component production, reducing power, and proton efflux may be related to acid tolerance in strain F77. The expression of these acid production- and acid tolerance-related genes was observed to be increased by biotite in strain F77. Our findings may help to elucidate the molecular mechanisms governing mineral weathering and, especially, acid tolerance in mineral-weathering bacteria.

scholarly journals Identification of a novel type of glucose dehydrogenase involved in the mineral weathering ability of Collimonas pratensis strain PMB3(1)

2020 ◽  
Author(s):  
L Picard ◽  
M-P Turpault ◽  
P M Oger ◽  
S Uroz
Keyword(s):  
Gluconic Acid ◽  
Molecular Mechanisms ◽  
Glucose Dehydrogenase ◽  
Random Mutagenesis ◽  
Mineral Weathering ◽  
Single Type ◽  
Biotite Weathering ◽  
Genomic Regions ◽  
Oxidation Of Glucose

Abstract The exact molecular mechanisms as well as the genes involved in the mineral weathering (MW) process by bacteria remain poorly characterized. To date, a single type of glucose dehydrogenase (GDH) depending on a particular co-factor named pyrroloquinoline quinone (PQQ) is known. These enzymes allow the production of gluconic acid through the oxidation of glucose. However, it remains to be determined how bacteria missing PQQ-dependent GDH and/or the related pqq biogenesis genes weather minerals. In this study, we considered the very effective mineral weathering bacterial strain PMB3(1) of Collimonas pratensis. Genome analysis revealed that it does not possess the PQQ based system. The use of random mutagenesis, gene complementation and functional assays allowed us to identify mutants impacted in their ability to weather mineral. Among them, three mutants were strongly altered on their acidification and biotite weathering abilities (58 to 75% of reduction compared to WT) and did not produce gluconic acid. The characterization of the genomic regions allowed noticeably to the identification of a Glucose/Methanol/Choline oxidoreductase. This region appeared very conserved among collimonads and related genera. This study represents the first demonstration of the implication of a PQQ-independent GDH in the mineral weathering process and explains how Collimonas weather minerals.

scholarly journals Expression of Plasmodium vivaxcrt-oIs Related to Parasite Stage but NotEx VivoChloroquine Susceptibility

2015 ◽  
Vol 60 (1) ◽  
pp. 361-367 ◽  
Author(s):  
Zuleima Pava ◽  
Irene Handayuni ◽  
Grennady Wirjanata ◽  
Sheren To ◽  
Leily Trianty ◽  
...  
Keyword(s):  
Gene Expression ◽  
Molecular Mechanisms ◽  
Ex Vivo ◽  
Drug Susceptibility ◽  
Fold Change ◽  
Low Grade ◽  
Content Type ◽  
Expression Levels ◽  
Stage Of Development ◽  
Parasite Stage

ABSTRACTChloroquine (CQ)-resistantPlasmodium vivaxis present in most countries whereP. vivaxinfection is endemic, but the underlying molecular mechanisms responsible remain unknown. Increased expression ofP. vivaxcrt-o(pvcrt-o) has been correlated within vivoCQ resistance in an area with low-grade resistance. We assessedpvcrt-oexpression in isolates from Papua (Indonesia), whereP. vivaxis highly CQ resistant.Ex vivodrug susceptibilities to CQ, amodiaquine, piperaquine, mefloquine, and artesunate were determined using a modified schizont maturation assay. Expression levels ofpvcrt-owere measured using a novel real-time quantitative reverse transcription-PCR method. Large variations inpvcrt-oexpression were observed across the 51 isolates evaluated, with the fold change in expression level ranging from 0.01 to 59 relative to that seen with theP. vivaxβ-tubulin gene and from 0.01 to 24 relative to that seen with theP. vivaxaldolase gene. Expression was significantly higher in isolates with the majority of parasites at the ring stage of development (median fold change, 1.7) compared to those at the trophozoite stage (median fold change, 0.5;P< 0.001). Twenty-nine isolates fulfilled the criteria forex vivodrug susceptibility testing and showed high variability in CQ responses (median, 107.9 [range, 6.5 to 345.7] nM). After controlling for the parasite stage, we found thatpvcrt-oexpression levels did not correlate with theex vivoresponse to CQ or with that to any of the other antimalarials tested. Our results highlight the importance of development-stage composition for measuringpvcrt-oexpression and suggest thatpvcrt-otranscription is not a primary determinant ofex vivodrug susceptibility. A comprehensive transcriptomic approach is warranted for an in-depth investigation of the role of gene expression levels andP. vivaxdrug resistance.

scholarly journals Molecular Mechanisms Contributing to the Growth and Physiology of an Extremophile Cultured with Dielectric Heating

2016 ◽  
Vol 82 (20) ◽  
pp. 6233-6246 ◽  
Author(s):  
Kathleen D. Cusick ◽  
Baochuan Lin ◽  
Anthony P. Malanoski ◽  
Sarah M. Strycharz-Glaven ◽  
Allison Cockrell-Zugell ◽  
...  
Keyword(s):  
Gene Expression ◽  
Microwave Heating ◽  
Defense Mechanisms ◽  
Molecular Mechanisms ◽  
Acid Metabolism ◽  
Expression Data ◽  
Dielectric Heating ◽  
Molecular Processes ◽  
Content Type ◽  
Differential Gene

ABSTRACTThe effect of microwave frequency electromagnetic fields on living microorganisms is an active and highly contested area of research. One of the major drawbacks to using mesophilic organisms to study microwave radiation effects is the unavoidable heating of the organism, which has limited the scale (<5 ml) and duration (<1 h) of experiments. However, the negative effects of heating a mesophile can be mitigated by employing thermophiles (organisms able to grow at temperatures of >60°C). This study identified changes in global gene expression profiles during the growth ofThermus scotoductusSA-01 at 65°C using dielectric (2.45 GHz, i.e., microwave) heating. RNA sequencing was performed on cultures at 8, 14, and 24 h after inoculation to determine the molecular mechanisms contributing to long-term cellular growth and survival under microwave heating conditions. Over the course of growth, genes associated with amino acid metabolism, carbohydrate metabolism, and defense mechanisms were upregulated; the number of repressed genes with unknown function increased; and at all time points, transposases were upregulated. Genes involved in cell wall biogenesis and elongation were also upregulated, consistent with the distinct elongated cell morphology observed after 24 h using microwave heating. Analysis of the global differential gene expression data enabled the identification of molecular processes specific to the response ofT. scotoductusSA-01 to dielectric heating during growth.IMPORTANCEThe residual heating of living organisms in the microwave region of the electromagnetic spectrum has complicated the identification of radiation-only effects using microorganisms for 50 years. A majority of the previous experiments used either mature cells or short exposure times with low-energy high-frequency radiation. Using global differential gene expression data, we identified molecular processes unique to dielectric heating usingThermus scotoductusSA-01 cultured over 30 h in a commercial microwave digestor. Genes associated with amino acid metabolism, carbohydrate metabolism, and defense mechanisms were upregulated; the number of repressed genes with unknown function increased; and at all time points, transposases were upregulated. These findings serve as a platform for future studies with mesophiles in order to better understand the response of microorganisms to microwave radiation.

scholarly journals Genome-Wide Mapping of Histone H3 Lysine 4 Trimethylation (H3K4me3) and Its Involvement in Fatty Acid Biosynthesis in Sunflower Developing Seeds

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 706
Author(s):  
Antonio J. Moreno-Pérez ◽  
Raquel Martins-Noguerol ◽  
Cristina DeAndrés-Gil ◽  
Mónica Venegas-Calerón ◽  
Rosario Sánchez ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Chromatin Remodeling ◽  
Molecular Mechanisms ◽  
Acid Metabolism ◽  
Fatty Acid Biosynthesis ◽  
Acid Synthesis ◽  
Sunflower Seeds ◽  
Acid Biosynthesis ◽  
Functional Regions ◽  
Genome Wide

Histone modifications are of paramount importance during plant development. Investigating chromatin remodeling in developing oilseeds sheds light on the molecular mechanisms controlling fatty acid metabolism and facilitates the identification of new functional regions in oil crop genomes. The present study characterizes the epigenetic modifications H3K4me3 in relationship with the expression of fatty acid-related genes and transcription factors in developing sunflower seeds. Two master transcriptional regulators identified in this analysis, VIV1 (homologous to Arabidopsis ABI3) and FUS3, cooperate in the regulation of WRINKLED 1, a transcriptional factor regulating glycolysis, and fatty acid synthesis in developing oilseeds.

scholarly journals Wnt5A modulates integrin expression in a receptor-dependent manner in ovarian cancer cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Vajihe Azimian-Zavareh ◽  
Zeinab Dehghani-Ghobadi ◽  
Marzieh Ebrahimi ◽  
Kian Mirzazadeh ◽  
Irina Nazarenko ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Cell Proliferation ◽  
Cell Attachment ◽  
Ovarian Cancer Cells ◽  
Integrin Expression ◽  
Dependent Manner ◽  
Cancer Cell Proliferation ◽  
Expression Levels ◽  
Multicellular Aggregates ◽  
Focal Adhesion Kinase Activity

AbstractWnt5A signals through various receptors that confer versatile biological functions. Here, we used Wnt5A overexpressing human ovarian SKOV-3 and OVCAR-3 stable clones for assessing integrin expression, cell proliferation, migration, invasion, and the ability of multicellular aggregates (MCAs) formation. We found here, that Wnt5A regulates differently the expression of its receptors in the stable Wnt5A overexpressing clones. The expression levels of Frizzled (FZD)-2 and -5, were increased in different clones. However ROR-1, -2 expression levels were differently regulated in clones. Wnt5A overexpressing clones showed increased cell proliferation, migration, and clonogenicity. Moreover, Wnt5A overexpressing SKOV-3 clone showed increased MCAs formation ability. Cell invasion had been increased in OVCAR-3-derived clones, while this was decreased in SKOV-3-derived clone. Importantly, αv integrin expression levels were increased in all assessed clones, accompanied by increased cell attachment to fibronectin and focal adhesion kinase activity. Moreover, the treatment of clones with Box5 as a Wnt5A/FZD5 antagonist abrogates ITGAV increase, cell proliferation, migration, and their attachment to fibronectin. Accordingly, we observed significantly higher expression levels of ITGAV and ITGB3 in human high-grade serous ovarian cancer specimens and ITGAV correlated positively with Wnt5A in metastatic serous type ovarian cancer. In summary, we hypothesize here, that Wnt5A/FZD-5 signaling modulate αv integrin expression levels that could be associated with ovarian cancer cell proliferation, migration, and fibronectin attachment.

scholarly journals Resistance and Heteroresistance to Colistin in Pseudomonas aeruginosa Isolates from Wenzhou, China

2019 ◽  
Vol 63 (10) ◽  
Author(s):  
Jie Lin ◽  
Chunquan Xu ◽  
Renchi Fang ◽  
Jianming Cao ◽  
Xiucai Zhang ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Lipid A ◽  
Population Analysis ◽  
Colistin Resistance ◽  
Content Type ◽  
Maldi Tof Ms ◽  
Expression Levels ◽  
Maldi Tof ◽  
Broth Microdilution Method ◽  
Tof Ms

ABSTRACT The goal was to investigate the mechanisms of colistin resistance and heteroresistance in Pseudomonas aeruginosa clinical isolates. Colistin resistance was determined by the broth microdilution method. Colistin heteroresistance was evaluated by population analysis profiling. Time-kill assays were also conducted. PCR sequencing was performed to detect the resistance genes among (hetero)resistant isolates, and quantitative real-time PCR assays were performed to determine their expression levels. Pulsed-field gel electrophoresis and multilocus sequence typing were performed. Lipid A characteristics were determined via matrix-assisted laser desorption–ionization time of flight mass spectrometry (MALDI-TOF MS). Two resistant isolates and 9 heteroresistant isolates were selected in this study. Substitutions in PmrB were detected in 2 resistant isolates. Among heteroresistant isolates, 8 of 9 heteroresistant isolates had nonsynonymous PmrB substitutions, and 2 isolates, including 1 with a PmrB substitution, had PhoQ alterations. Correspondingly, the expression levels of pmrA or phoP were upregulated in PmrB- or PhoQ-substituted isolates. One isolate also found alterations in ParRS and CprRS. The transcript levels of the pmrH gene were observed to increase across all investigated isolates. MALDI-TOF MS showed additional 4-amino-4-deoxy-l-arabinose (l-Ara4N) moieties in lipid A profiles in (hetero)resistant isolates. In conclusion, both colistin resistance and heteroresistance in P. aeruginosa in this study mainly involved alterations of the PmrAB regulatory system. There were strong associations between mutations in specific genetic loci for lipid A synthesis and regulation of modifications to lipid A. The transition of colistin heteroresistance to resistance should be addressed in future clinical surveillance.

scholarly journals Integrative iTRAQ-based proteomic and transcriptomic analysis reveals the accumulation patterns of key metabolites associated with oil quality during seed ripening of Camellia oleifera

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Zhouchen Ye ◽  
Jing Yu ◽  
Wuping Yan ◽  
Junfeng Zhang ◽  
Dongmei Yang ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Molecular Mechanisms ◽  
Acid Metabolism ◽  
Oil Quality ◽  
Gas Chromatography Mass Spectrometry ◽  
Glutathione Metabolism ◽  
Poor Correlation ◽  
Camellia Oleifera ◽  
Specific Expression

AbstractCamellia oleifera (C. oleifera) is one of the four major woody oil-bearing crops in the world and has relatively high ecological, economic, and medicinal value. Its seeds undergo a series of complex physiological and biochemical changes during ripening, which is mainly manifested as the accumulation and transformation of certain metabolites closely related to oil quality, especially flavonoids and fatty acids. To obtain new insights into the underlying molecular mechanisms, a parallel analysis of the transcriptome and proteome profiles of C. oleifera seeds at different maturity levels was conducted using RNA sequencing (RNA-seq) and isobaric tags for relative and absolute quantification (iTRAQ) complemented with gas chromatography-mass spectrometry (GC-MS) data. A total of 16,530 transcripts and 1228 proteins were recognized with significant differential abundances in pairwise comparisons of samples at various developmental stages. Among these, 317 were coexpressed with a poor correlation, and most were involved in metabolic processes, including fatty acid metabolism, α-linolenic acid metabolism, and glutathione metabolism. In addition, the content of total flavonoids decreased gradually with seed maturity, and the levels of fatty acids generally peaked at the fat accumulation stage; these results basically agreed with the regulation patterns of genes or proteins in the corresponding pathways. The expression levels of proteins annotated as upstream candidates of phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS) as well as their cognate transcripts were positively correlated with the variation in the flavonoid content, while shikimate O-hydroxycinnamoyltransferase (HCT)-encoding genes had the opposite pattern. The increase in the abundance of proteins and mRNAs corresponding to alcohol dehydrogenase (ADH) was associated with a reduction in linoleic acid synthesis. Using weighted gene coexpression network analysis (WGCNA), we further identified six unique modules related to flavonoid, oil, and fatty acid anabolism that contained hub genes or proteins similar to transcription factors (TFs), such as MADS intervening keratin-like and C-terminal (MIKC_MADS), type-B authentic response regulator (ARR-B), and basic helix-loop-helix (bHLH). Finally, based on the known metabolic pathways and WGCNA combined with the correlation analysis, five coexpressed transcripts and proteins composed of cinnamyl-alcohol dehydrogenases (CADs), caffeic acid 3-O-methyltransferase (COMT), flavonol synthase (FLS), and 4-coumarate: CoA ligase (4CL) were screened out. With this exploratory multiomics dataset, our results presented a dynamic picture regarding the maturation process of C. oleifera seeds on Hainan Island, not only revealing the temporal specific expression of key candidate genes and proteins but also providing a scientific basis for the genetic improvement of this tree species.

scholarly journals YWHAZ interacts with DAAM1 to promote cell migration in breast cancer

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Jie Mei ◽  
Yan Liu ◽  
Xinqian Yu ◽  
Leiyu Hao ◽  
Tao Ma ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Poor Prognosis ◽  
Molecular Mechanisms ◽  
Transcriptional Regulator ◽  
Expression Levels ◽  
Functional Roles ◽  
Normal Tissues ◽  
Rhoa Activation ◽  
Promote Cell Migration

AbstractDishevelled-associated activator of morphogenesis 1 (DAAM1) is a critical driver in facilitating metastasis in breast cancer (BrCa). However, molecular mechanisms for the regulation of DAAM1 activation are only partially elucidated. In this research, the expression levels of YWHAZ and DAAM1 were examined by immunohistochemistry (IHC) staining in BrCa tissues. The functional roles of tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein zeta (YWHAZ)–DAAM1 axis and their regulator microRNA-613 (miR-613) in BrCa cells and associated molecular mechanisms were demonstrated in vitro. As results, the expression levels of DAAM1 and YWHAZ were significantly upregulated in BrCa tissues compared with normal tissues and remarkably associated with poor prognosis. Besides, DAAM1 and YWHAZ were positively correlated with each other in BrCa tissues. YWHAZ interacted and colocalized with DAAM1 in BrCa cells, which was essential for DAAM1-mediated microfilament remodeling and RhoA activation. Moreover, miR-613 directly targeted both YWHAZ and DAAM1, contributing to inhibiting BrCa cells migration via blocking the complex of YWHAZ–DAAM1. To sum up, these data reveal that YWHAZ regulates DAAM1 activation, and the YWHAZ–DAAM1 complex is directly targeted by the shared post-transcriptional regulator miR-613.

scholarly journals Natural Disruption of Two Regulatory Networks in Serotype M3 Group A Streptococcus Isolates Contributes to the Virulence Factor Profile of This Hypervirulent Serotype

2014 ◽  
Vol 82 (5) ◽  
pp. 1744-1754 ◽  
Author(s):  
Tram N. Cao ◽  
Zhuyun Liu ◽  
Tran H. Cao ◽  
Kathryn J. Pflughoeft ◽  
Jeanette Treviño ◽  
...  
Keyword(s):  
Virulence Factor ◽  
Regulatory Networks ◽  
Molecular Mechanisms ◽  
Group A Streptococcus ◽  
Regulatory System ◽  
Mrna Levels ◽  
Bacterial Strains ◽  
Content Type ◽  
Small Regulatory Rna ◽  
Group A

ABSTRACTDespite the public health challenges associated with the emergence of new pathogenic bacterial strains and/or serotypes, there is a dearth of information regarding the molecular mechanisms that drive this variation. Here, we began to address the mechanisms behind serotype-specific variation between serotype M1 and M3 strains of the human pathogenStreptococcus pyogenes(the group AStreptococcus[GAS]). Spatially diverse contemporary clinical serotype M3 isolates were discovered to contain identical inactivating mutations within genes encoding two regulatory systems that control the expression of important virulence factors, including the thrombolytic agent streptokinase, the protease inhibitor-binding protein-G-related α2-macroglobulin-binding (GRAB) protein, and the antiphagocytic hyaluronic acid capsule. Subsequent analysis of a larger collection of isolates determined that M3 GAS, since at least the 1920s, has harbored a 4-bp deletion in thefasCgene of thefasBCAXregulatory system and an inactivating polymorphism in therivRregulator-encoding gene. ThefasCandrivRmutations in M3 isolates directly affect the virulence factor profile of M3 GAS, as evident by a reduction in streptokinase expression and an enhancement of GRAB expression. Complementation of thefasCmutation in M3 GAS significantly enhanced levels of the small regulatory RNA FasX, which in turn enhanced streptokinase expression. Complementation of therivRmutation in M3 GAS restored the regulation ofgrabmRNA abundance but did not alter capsule mRNA levels. While important, thefasCandrivRmutations do not provide a full explanation for why serotype M3 strains are associated with unusually severe invasive infections; thus, further investigation is warranted.

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