scholarly journals Role of Ribonucleotide Reductase in Bacillus subtilis Stress-Associated Mutagenesis

2016 ◽  
Vol 199 (4) ◽  
Author(s):  
Karla Viridiana Castro-Cerritos ◽  
Ronald E. Yasbin ◽  
Eduardo A. Robleto ◽  
Mario Pedraza-Reyes
Keyword(s):  
Bacillus Subtilis ◽  
Ribonucleotide Reductase ◽  
Single Class ◽  
Content Type ◽  
Conditional Mutant ◽  
Dna Replication And Repair ◽  
Metabolic Conditions ◽  
Study Support ◽  
Encoding Genes

ABSTRACT The Gram-positive microorganism Bacillus subtilis relies on a single class Ib ribonucleotide reductase (RNR) to generate 2′-deoxyribonucleotides (dNDPs) for DNA replication and repair. In this work, we investigated the influence of RNR levels on B. subtilis stationary-phase-associated mutagenesis (SPM). Since RNR is essential in this bacterium, we engineered a conditional mutant of strain B. subtilis YB955 (hisC952 metB5 leu427) in which expression of the nrdEF operon was modulated by isopropyl-β-d-thiogalactopyranoside (IPTG). Moreover, genetic inactivation of ytcG, predicted to encode a repressor (NrdR) of nrdEF in this strain, dramatically increased the expression levels of a transcriptional nrdE-lacZ fusion. The frequencies of mutations conferring amino acid prototrophy in three genes were measured in cultures under conditions that repressed or induced RNR-encoding genes. The results revealed that RNR was necessary for SPM and overexpression of nrdEF promoted growth-dependent mutagenesis and SPM. We also found that nrdEF expression was induced by H2O2 and such induction was dependent on the master regulator PerR. These observations strongly suggest that the metabolic conditions operating in starved B. subtilis cells increase the levels of RNR, which have a direct impact on SPM. IMPORTANCE Results presented in this study support the concept that the adverse metabolic conditions prevailing in nutritionally stressed bacteria activate an oxidative stress response that disturbs ribonucleotide reductase (RNR) levels. Such an alteration of RNR levels promotes mutagenic events that allow Bacillus subtilis to escape from growth-limited conditions.

scholarly journals Molecular Basis of Substrate Recognition of Endonuclease Q from the Euryarchaeon Pyrococcus furiosus

2019 ◽  
Vol 202 (2) ◽  
Author(s):  
Miyako Shiraishi ◽  
Shigenori Iwai
Keyword(s):  
Dna Repair ◽  
Bacillus Subtilis ◽  
Substrate Specificity ◽  
Molecular Basis ◽  
Pyrococcus Furiosus ◽  
Substrate Recognition ◽  
Base Flipping ◽  
Content Type ◽  
Cleavage Activity

ABSTRACT Endonuclease Q (EndoQ), a DNA repair endonuclease, was originally identified in the hyperthermophilic euryarchaeon Pyrococcus furiosus in 2015. EndoQ initiates DNA repair by generating a nick on DNA strands containing deaminated bases and an abasic site. Although EndoQ is thought to be important for maintaining genome integrity in certain bacteria and archaea, the underlying mechanism catalyzed by EndoQ remains unclear. Here, we provide insights into the molecular basis of substrate recognition by EndoQ from P. furiosus (PfuEndoQ) using biochemical approaches. Our results of the substrate specificity range and the kinetic properties of PfuEndoQ demonstrate that PfuEndoQ prefers the imide structure in nucleobases along with the discovery of its cleavage activity toward 5,6-dihydrouracil, 5-hydroxyuracil, 5-hydroxycytosine, and uridine in DNA. The combined results for EndoQ substrate binding and cleavage activity analyses indicated that PfuEndoQ flips the target base from the DNA duplex, and the cleavage activity is highly dependent on spontaneous base flipping of the target base. Furthermore, we find that PfuEndoQ has a relatively relaxed substrate specificity; therefore, the role of EndoQ in restriction modification systems was explored. The activity of the EndoQ homolog from Bacillus subtilis was found not to be inhibited by the uracil glycosylase inhibitor from B. subtilis bacteriophage PBS1, whose genome is completely replaced by uracil instead of thymine. Our findings suggest that EndoQ not only has additional functions in DNA repair but also could act as an antiviral enzyme in organisms with EndoQ. IMPORTANCE Endonuclease Q (EndoQ) is a lesion-specific DNA repair enzyme present in certain bacteria and archaea. To date, it remains unclear how EndoQ recognizes damaged bases. Understanding the mechanism of substrate recognition by EndoQ is important to grasp genome maintenance systems in organisms with EndoQ. Here, we find that EndoQ from the euryarchaeon Pyrococcus furiosus recognizes the imide structure in nucleobases by base flipping, and the cleavage activity is enhanced by the base pair instability of the target base, along with the discovery of its cleavage activity toward 5,6-dihydrouracil, 5-hydroxyuracil, 5-hydroxycytosine, and uridine in DNA. Furthermore, a potential role of EndoQ in Bacillus subtilis as an antiviral enzyme by digesting viral genome is demonstrated.

scholarly journals Role of SpoIVA ATPase Motifs during Clostridioides difficile Sporulation

2020 ◽  
Vol 202 (21) ◽  
Author(s):  
Hector Benito de la Puebla ◽  
David Giacalone ◽  
Alexei Cooper ◽  
Aimee Shen
Keyword(s):  
Bacillus Subtilis ◽  
Atp Hydrolysis ◽  
Spore Formation ◽  
Spore Form ◽  
Content Type ◽  
Clostridioides Difficile ◽  
Allele Specific ◽  
Coat Layer ◽  
Quality Control Mechanism

ABSTRACT The nosocomial pathogen Clostridioides difficile is a spore-forming obligate anaerobe that depends on its aerotolerant spore form to transmit infections. Functional spore formation depends on the assembly of a proteinaceous layer known as the coat around the developing spore. In C. difficile, coat assembly depends on the conserved spore protein SpoIVA and the clostridial-organism-specific spore protein SipL, which directly interact. Mutations that disrupt their interaction cause the coat to mislocalize and impair spore formation. In Bacillus subtilis, SpoIVA is an ATPase that uses ATP hydrolysis to drive its polymerization around the forespore. Loss of SpoIVA ATPase activity impairs B. subtilis SpoIVA encasement of the forespore and activates a quality control mechanism that eliminates these defective cells. Since this mechanism is lacking in C. difficile, we tested whether mutations in the C. difficile SpoIVA ATPase motifs impact functional spore formation. Disrupting C. difficile SpoIVA ATPase motifs resulted in phenotypes that were typically >104-fold less severe than the equivalent mutations in B. subtilis. Interestingly, mutation of ATPase motif residues predicted to abrogate SpoIVA binding to ATP decreased the SpoIVA-SipL interaction, whereas mutation of ATPase motif residues predicted to disrupt ATP hydrolysis but maintain ATP binding enhanced the SpoIVA-SipL interaction. When a sipL mutation known to reduce binding to SpoIVA was combined with a spoIVA mutation predicted to prevent SpoIVA binding to ATP, spore formation was severely exacerbated. Since this phenotype is allele specific, our data imply that SipL recognizes the ATP-bound form of SpoIVA and highlight the importance of this interaction for functional C. difficile spore formation. IMPORTANCE The major pathogen Clostridioides difficile depends on its spore form to transmit disease. However, the mechanism by which C. difficile assembles spores remains poorly characterized. We previously showed that binding between the spore morphogenetic proteins SpoIVA and SipL regulates assembly of the protective coat layer around the forespore. In this study, we determined that mutations in the C. difficile SpoIVA ATPase motifs result in relatively minor defects in spore formation, in contrast with Bacillus subtilis. Nevertheless, our data suggest that SipL preferentially recognizes the ATP-bound form of SpoIVA and identify a specific residue in the SipL C-terminal LysM domain that is critical for recognizing the ATP-bound form of SpoIVA. These findings advance our understanding of how SpoIVA-SipL interactions regulate C. difficile spore assembly.

scholarly journals Regulatory Activities of Four ArsR Proteins in Agrobacterium tumefaciens 5A

2016 ◽  
Vol 82 (12) ◽  
pp. 3471-3480 ◽  
Author(s):  
Yoon-Suk Kang ◽  
Keenan Brame ◽  
Jonathan Jetter ◽  
Brian B. Bothner ◽  
Gejiao Wang ◽  
...  
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Content Type ◽  
Variable Control ◽  
Protein Primary Structure ◽  
Multiple Copies ◽  
Reporter Assays ◽  
Type Gene ◽  
Encoding Genes ◽  
Complex Regulatory Network

ABSTRACTArsR is a well-studied transcriptional repressor that regulates microbe-arsenic interactions. Most microorganisms have anarsRgene, but in cases where multiple copies exist, the respective roles or potential functional overlap have not been explored. We examined the repressors encoded byarsR1andarsR2(ars1operon) and byarsR3andarsR4(ars2operon) inAgrobacterium tumefaciens5A. ArsR1 and ArsR4 are very similar in their primary sequences and diverge phylogenetically from ArsR2 and ArsR3, which are also quite similar to one another. Reporter constructs (lacZ) forarsR1,arsR2, andarsR4were all inducible by As(III), but expression ofarsR3(monitored by reverse transcriptase PCR) was not influenced by As(III) and appeared to be linked transcriptionally to an upstreamlysR-type gene. Experiments using a combination of deletion mutations and additional reporter assays illustrated that the encoded repressors (i) are not all autoregulatory as is typically known for ArsR proteins, (ii) exhibit variable control of each other's encoding genes, and (iii) exert variable control of other genes previously shown to be under the control of ArsR1. Furthermore, ArsR2, ArsR3, and ArsR4 appear to have an activator-like function for some genes otherwise repressed by ArsR1, which deviates from the well-studied repressor role of ArsR proteins. The differential regulatory activities suggest a complex regulatory network not previously observed in ArsR studies. The results indicate that fine-scale ArsR sequence deviations of the reiterated regulatory proteins apparently translate to different regulatory roles.IMPORTANCEGiven the significance of the ArsR repressor in regulating various aspects of microbe-arsenic interactions, it is important to assess potential regulatory overlap and/or interference when a microorganism carries multiple copies ofarsR. This study explores this issue and shows that the fourarsRgenes inA. tumefaciens5A, associated with two separatearsoperons, encode proteins exhibiting various degrees of functional overlap with respect to autoregulation and cross-regulation, as well as control of other functional genes. In some cases, differences in regulatory activity are associated with only limited differences in protein primary structure. The experiments summarized herein also present evidence that ArsR proteins appear to have activator functions, representing novel regulatory activities for ArsR, previously known only to be a repressor.

scholarly journals Functional Characterization of Burkholderia pseudomallei Trimeric Autotransporters

2013 ◽  
Vol 81 (8) ◽  
pp. 2788-2799 ◽  
Author(s):  
Cristine G. Campos ◽  
Matthew S. Byrd ◽  
Peggy A. Cotter
Keyword(s):  
Burkholderia Pseudomallei ◽  
Functional Characterization ◽  
A549 Cells ◽  
Content Type ◽  
Tier 1 ◽  
Type V ◽  
Mouse Model Of Infection ◽  
Encoding Genes

ABSTRACTBurkholderia pseudomalleiis a tier 1 select agent and the causative agent of melioidosis, a severe and often fatal disease with symptoms ranging from acute pneumonia and septic shock to a chronic infection characterized by abscess formation in the lungs, liver, and spleen. Autotransporters (ATs) are exoproteins belonging to the type V secretion system family, with many playing roles in pathogenesis. The genome ofB. pseudomalleistrain 1026b encodes nine putative trimeric AT proteins, of which only four have been described. Using a bioinformatic approach, we annotated putative domains within each trimeric AT protein, excluding the well-studied BimA protein, and found short repeated sequences unique toBurkholderiaspecies, as well as an unexpectedly large proportion of ATs with extended signal peptide regions (ESPRs). To characterize the role of trimeric ATs in pathogenesis, we constructed disruption or deletion mutations in each of eight AT-encoding genes and evaluated the resulting strains for adherence to, invasion of, and plaque formation in A549 cells. The majority of the ATs (and/or the proteins encoded downstream) contributed to adherence to and efficient invasion of A549 cells. Using a BALB/c mouse model of infection, we determined the contributions of each AT to bacterial burdens in the lungs, liver, and spleen. At 48 h postinoculation, only one strain, Bp340::pDbpaC, demonstrated a defect in dissemination and/or survival in the liver, indicating that BpaC is required for wild-type virulence in this model.

China's OFDI policy announcements and cross-border M&A

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fredrik Utesch-Xiong
Keyword(s):  
Policy Change ◽  
Negative Binomial ◽  
Change Theory ◽  
Content Type ◽  
Policy Effect ◽  
Cross Border ◽  
Firm Internationalization ◽  
Study Support ◽  
Policy Types

PurposeThis paper aims to enhance the understanding of the role of Chinese outward foreign direct investment (OFDI) policies for cross-border merger and acquisition (M&A) by distinguishing between coercive and noncoercive OFDI policies.Design/methodology/approachThe dependent variable is the count of completed M&A transactions, measured monthly. Due to the nature of the study’s data, the author performs a zero-inflated negative binomial (ZINB) regression.FindingsSeparating between coercive and noncoercive policies, the author finds that the latter type shows a stronger supportive effect on the count of M&A deals. Considering firm ownership, the study’s results reveal that announcements of coercive policies have a weaker effect on cross-border M&A for state-owned enterprises (SOEs) than that for private-owned enterprises (POEs). For local SOEs (LSOEs) and central SOEs (CSOEs), this difference becomes even larger with noncoercive policy announcements. The influence on M&A of both policy types gets partially replaced with increasing internationalization experience.Originality/valueCombining institutional theory with policy change theory, the author argues that international business (IB) research on policy change needs to consider the integration of theoretical policy-level approaches to catch the effects of policy change on firm internationalization appropriately. The findings of the study support this argument by highlighting that the policy effect differs by policy type.

scholarly journals Characterization of the Pneumocystis carinii Histone Acetyltransferase Chaperone Proteins PcAsf1 and PcVps75

2013 ◽  
Vol 81 (6) ◽  
pp. 2268-2275 ◽  
Author(s):  
Jakrapun Pupaibool ◽  
Theodore J. Kottom ◽  
Kelly Bouchonville ◽  
Andrew H. Limper
Keyword(s):  
Dna Replication ◽  
Cell Cycle Progression ◽  
Pneumocystis Carinii ◽  
Histone H3 ◽  
Content Type ◽  
Dna Replication And Repair ◽  
Opportunistic Fungal Pathogen ◽  
Vacuolar Protein

ABSTRACTRtt109 is a lysine acetyltransferase that acetylates histone H3 at lysine 56 (H3K56) in fungi. This acetylation event is important for proper DNA replication and repair to occur. Efficient Rtt109 acetyltransferase activity also requires a histone chaperone, vacuolar protein sorting 75 (Vps75), as well as the major chaperone of the H3-H4 dimer, anti-silencing factor 1 (Asf1). Little is known about the role of these proteins in the opportunistic fungal pathogenPneumocystis carinii. To investigate the functions of Asf1 and Vps75 inPneumocystis carinii, we cloned and characterized both of these genes. Here, we demonstrate that both genes,P. carinii asf1(Pcasf1) andPcvps75, function in a fashion analogous to theirSaccharomyces cerevisiaecounterparts. We demonstrate that bothP. cariniiAsf1 (PcAsf1) and PcVps75 can bind histones. Furthermore, whenPcasf1is expressed heterologously inS. cerevisiae asf1Δ cells, PcAsf1 can restore full H3 lysine acetylation. We further demonstrated that thePcasf1cDNA expressed inasf1ΔS. cerevisiaecells can restore growth to wild-type levels in the presence of genotoxic agents that block DNA replication. Lastly, we observed that purified PcAsf1 and PcVps75 proteins enhance the ability of PcRtt109 to acetylate histone H3-H4 tetramers. Together, our results indicate that the functions of the Rtt109-Asf1-Vps75 complex in the acetylation of histone H3 lysine 56 and in DNA damage response are present inP. cariniiDNA and cell cycle progression.

scholarly journals A LysM Domain Intervenes in Sequential Protein-Protein and Protein-Peptidoglycan Interactions Important for Spore Coat Assembly inBacillus subtilis

2018 ◽  
Vol 201 (4) ◽  
Author(s):  
Fatima C. Pereira ◽  
Filipa Nunes ◽  
Fernando Cruz ◽  
Catarina Fernandes ◽  
Anabela L. Isidro ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Protein Interaction ◽  
Interaction Domain ◽  
Content Type ◽  
Protein Protein Interaction ◽  
Lysm Domain ◽  
Binding Function ◽  
Morphogenetic Protein ◽  
Tight Connection

ABSTRACTAt a late stage in spore development inBacillus subtilis, the mother cell directs synthesis of a layer of peptidoglycan known as the cortex between the two forespore membranes, as well as the assembly of a protective protein coat at the surface of the forespore outer membrane. SafA, the key determinant of inner coat assembly, is first recruited to the surface of the developing spore and then encases the spore under the control of the morphogenetic protein SpoVID. SafA has a LysM peptidoglycan-binding domain, SafALysM, and localizes to the cortex-coat interface in mature spores. SafALysMis followed by a region, A, required for an interaction with SpoVID and encasement. We now show that residues D10 and N30 in SafALysM, while involved in the interaction with peptidoglycan, are also required for the interaction with SpoVID and encasement. We further show that single alanine substitutions on residues S11, L12, and I39 of SafALysMthat strongly impair binding to purified cortex peptidoglycan affect a later stage in the localization of SafA that is also dependent on the activity of SpoVE, a transglycosylase required for cortex formation. The assembly of SafA thus involves sequential protein-protein and protein-peptidoglycan interactions, mediated by the LysM domain, which are required first for encasement then for the final localization of the protein in mature spores.IMPORTANCEBacillus subtilisspores are encased in a multiprotein coat that surrounds an underlying peptidoglycan layer, the cortex. How the connection between the two layers is enforced is not well established. Here, we elucidate the role of the peptidoglycan-binding LysM domain, present in two proteins, SafA and SpoVID, that govern the localization of additional proteins to the coat. We found that SafALysMis a protein-protein interaction module during the early stages of coat assembly and a cortex-binding module at late stages in morphogenesis, with the cortex-binding function promoting a tight connection between the cortex and the coat. In contrast, SpoVIDLysMfunctions only as a protein-protein interaction domain that targets SpoVID to the spore surface at the onset of coat assembly.

The effect of leader personality on follower behaviour

2018 ◽  
Vol 39 (1) ◽  
pp. 14-33 ◽  
Author(s):  
Mehmet Kahya ◽  
Faruk Şahin
Keyword(s):  
Task Performance ◽  
Mediating Effect ◽  
Content Type ◽  
Mediating Role ◽  
Member Exchange ◽  
Study Support ◽  
Satisfaction With The Leader ◽  
Performance Satisfaction ◽  
The Relationship

Purpose The purpose of this paper is to examine the mediating effect of the leader-member exchange (LMX) on the relationship between leader personality and follower attitudes and behaviours, including task performance, satisfaction with the leader and organisational citizenship behaviour. Design/methodology/approach Adopting a multifaceted perspective to examine the relationships among the research variables, data were collected from 67 leaders and 372 followers. To test the hypotheses, hierarchical linear modelling analyses were conducted. Findings The results indicate that leader extraversion is positively related to follower task performance and that leader agreeableness is positively related to follower organisational citizenship behaviour and satisfaction with leaders. Moreover, the results indicate that the quality of the LMX relationship partially mediated the positive relationship between leader extraversion and follower task performance and fully mediated the relationship between leader agreeableness and satisfaction with leader and organisational citizenship behaviour. Practical implications The findings of this study support the mediating role of the LMX relationship between leader personality and follower attitudes and behaviours. Hence, it is worthwhile to examine the effects of leader personality in an organisational context. Originality/value The originality of this study is that it focusses on the integration of leader personality, LMX, and follower attitudes and behaviours in a single study, providing a model that indicates the mediating role of LMX in the relationship between leader personality and follower attitudes and behaviours.

scholarly journals Protective Role of Spore Structural Components in Determining Bacillus subtilis Spore Resistance to Simulated Mars Surface Conditions

2012 ◽  
Vol 78 (24) ◽  
pp. 8849-8853 ◽  
Author(s):  
Ralf Moeller ◽  
Andrew C. Schuerger ◽  
Günther Reitz ◽  
Wayne L. Nicholson
Keyword(s):  
Bacillus Subtilis ◽  
Dipicolinic Acid ◽  
Protective Role ◽  
Structural Components ◽  
Wild Type ◽  
Content Type ◽  
Surface Conditions ◽  
Bacillus Subtilis Spore ◽  
Spore Resistance

ABSTRACTSpores of wild-type and mutantBacillus subtilisstrains lacking various structural components were exposed to simulated Martian atmospheric and UV irradiation conditions. Spore survival and mutagenesis were strongly dependent on the functionality of all of the structural components, with small acid-soluble spore proteins, coat layers, and dipicolinic acid as key protectants.

scholarly journals Contribution of Surfactin and SwrA to Flagellin Expression, Swimming, and Surface Motility in Bacillus subtilis

2012 ◽  
Vol 78 (18) ◽  
pp. 6540-6544 ◽  
Author(s):  
Emilia Ghelardi ◽  
Sara Salvetti ◽  
Mara Ceragioli ◽  
Sokhna A. Gueye ◽  
Francesco Celandroni ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Essential Role ◽  
Flagellin Gene ◽  
Content Type ◽  
Low Humidity ◽  
Lipopeptide Biosurfactant ◽  
Surface Motility ◽  
Surfactin Production ◽  
Flagellar Genes

ABSTRACTMulticellular communities produced byBacillus subtiliscan adopt sliding or swarming to translocate over surfaces. While sliding is a flagellum-independent motility produced by the expansive forces in a growing colony, swarming requires flagellar functionality and is characterized by the appearance of hyperflagellated swarm cells that associate in bundles or rafts during movement. Previous work has shown that swarming by undomesticatedB. subtilisstrains requiresswrA, a gene that upregulates the expression of flagellar genes and increases swimming motility, and surfactin, a lipopeptide biosurfactant that also facilitates sliding. Through an analysis ofswrA+andswrAmutant laboratory strains with or without a mutation insfp(a gene involved in surfactin production), we show that bothswrAand surfactin upregulate the transcription of the flagellin gene and increase bacterial swimming. Surfactin also allows the nonswarmingswrAmutant strain to efficiently colonize moist surfaces by sliding. Finally, we reconfirm the essential role ofswrAin swarming and show that surfactin, which increases surface wettability, allowsswrA+strains to produce swarm cells on media at low humidity.

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