The unusual extended signal peptide region of the type V secretion system is phylogenetically restricted

ABSTRACT Proteins secreted by the type V secretion system possess multiple functions, including the capacity to mediate adhesion, aggregation, and biolfilm formation. The type V secretion system can be divided into five subclasses, one of which is the type Ve system. Proteins of the type Ve secretion system are also referred to as inverse autotransporters (IATs). In this study, we performed an in silico analysis of 126 completely sequenced Escherichia coli genomes available in the NCBI database and identified several distinct IAT-encoding gene families whose distribution varied throughout the E. coli phylogeny. The genes included three characterized IATs (intimin, fdeC, and yeeJ) and four uncharacterized IATs (here named iatA, iatB, iatC, and iatD). The four iat genes were cloned from the completely sequenced environmental E. coli strain SMS-3-5 and characterized. Three of these IAT proteins (IatB, IatC, and IatD) were expressed at the cell surface and possessed the capacity to mediate biofilm formation in a recombinant E. coli K-12 strain. Further analysis of the iatB gene, which showed a unique association with extraintestinal E. coli strains, suggested that its regulation is controlled by the LeuO global regulator. Overall, this study provides new data describing the prevalence, sequence variation, domain structure, function, and regulation of IATs found in E. coli. IMPORTANCE Escherichia coli is one of the most prevalent facultative anaerobes of the human gut. E. coli normally exists as a harmless commensal but can also cause disease following the acquisition of genes that enhance its pathogenicity. Adhesion is an important first step in colonization of the host and is mediated by an array of cell surface components. In E. coli, these include a family of adhesins secreted by the type V secretion system. Here, we identified and characterized new proteins from an emerging subclass of the type V secretion system known as the inverse autotransporters (IATs). We found that IAT-encoding genes are present in a wide range of strains and showed that three novel IATs were localized on the E. coli cell surface and mediated biofilm formation. Overall, this study provides new insight into the prevalence, function, and regulation of IATs in E. coli.

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A controllable expression-secretion vector constructed from the multiple trp promoter-operator, the signal peptide region of the ompF gene and the trpR gene in Escherichia coli.

Agricultural and Biological Chemistry ◽

10.1271/bbb1961.50.1295 ◽

1986 ◽

Vol 50 (5) ◽

pp. 1295-1302 ◽

Cited By ~ 2

Author(s):

Masao ITOH ◽

Hirofumi AIBA ◽

Kaoru INOKUCHI ◽

Takeshi MIZUNO ◽

Kenji NAGAHARI ◽

...

Keyword(s):

Escherichia Coli ◽

Signal Peptide ◽

Signal Peptide Region ◽

Secretion Vector ◽

Trp Promoter ◽

Peptide Region

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Non-HFE mutations in haemochromatosis in China: combination of heterozygous mutations involving HJV signal peptide variants

Journal of Medical Genetics ◽

10.1136/jmedgenet-2018-105348 ◽

2018 ◽

Vol 55 (10) ◽

pp. 650-660 ◽

Cited By ~ 8

Author(s):

Tingxia Lv ◽

Wei Zhang ◽

Anjian Xu ◽

Yanmeng Li ◽

Donghu Zhou ◽

...

Keyword(s):

Iron Overload ◽

Exome Sequencing ◽

Signal Peptide ◽

Chinese Patients ◽

Aetiological Factor ◽

Compound Heterozygous ◽

Common Mutation ◽

Smad Pathway ◽

Signal Peptide Region ◽

Peptide Region

IntroductionHereditary haemochromatosis (HH) caused by a homozygous p.C282Y mutation in haemochromatosis (HFE) gene has been well documented. However, less is known about the causative non-HFE mutation. We aimed to assess mutation patterns of haemochromatosis-related genes in Chinese patients with primary iron overload.MethodsPatients were preanalysed for mutations in the classic HH-related genes: HFE, HJV, HAMP, TFR2 and SLC40A1. Whole exome sequencing was conducted for cases with variants in HJV signal peptide region. Representative variants were analysed for biological function.ResultsNone of the cases analysed harboured the HFE p.C282Y; however, 21 of 22 primary iron-overload cases harboured at least one non-synonymous variant in the non-HFE genes. Specifically, p.E3D or p.Q6H variants in the HJV signal peptide region were identified in nine cases (40.9%). In two of three probands with the HJV p.E3D, exome sequencing identified accompanying variants in BMP/SMAD pathway genes, including TMPRSS6 p.T331M and BMP4 p.R269Q, and interestingly, SUGP2 p.R639Q was identified in all the three cases. Pedigree analysis showed a similar pattern of combination of heterozygous mutations in cases with HJV p.E3D or p.Q6H, with SUGP2 p.R639Q or HJV p.C321X being common mutation. In vitro siRNA interference of SUGP2 showed a novel role of downregulating the BMP/SMAD pathway. Site-directed mutagenesis of HJV p.Q6H/p.C321X in cell lines resulted in loss of membrane localisation of mutant HJV, and downregulation of p-SMAD1/5 and HAMP.ConclusionCompound heterozygous mutations of HJV or combined heterozygous mutations of BMP/SMAD pathway genes, marked by HJV variants in the signal peptide region, may represent a novel aetiological factor for HH.

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Expression of a Tranosema rostrale polydnavirus gene in the spruce budworm, Choristoneura fumiferana

Microbiology ◽

10.1099/0022-1317-81-7-1871 ◽

2000 ◽

Vol 81 (7) ◽

pp. 1871-1880 ◽

Cited By ~ 37

Author(s):

Catherine Béliveau ◽

Marlène Laforge ◽

Michel Cusson ◽

Guy Bellemare

Keyword(s):

Signal Peptide ◽

Fat Body ◽

Choristoneura Fumiferana ◽

Northern Analysis ◽

Juvenile Hormone Esterase ◽

Signal Peptide Region ◽

Putative Signal Peptide ◽

Cysteine Rich Protein ◽

Cellular Immune ◽

Peptide Region

The endoparasitic wasp Tranosema rostrale (Ichneumonidae) transmits a polydnavirus (PDV) to its host, Choristoneura fumiferana, during oviposition. Unlike most other PDVs examined, the virus of T. rostrale (TrPDV) does not appear to play an important role in suppressing the host cellular immune response. However, it inhibits host metamorphosis. In the present study, TrPDV gene expression was examined in parasitized and virus-injected last-instar caterpillars. Northern analysis with viral DNA as a probe revealed only one detectable mRNA, of about 650 bp. The corresponding cDNA, termed TrV1, was cloned and sequenced and found to encode a protein of 103 amino acids which, following cleavage of the putative signal peptide, has a predicted molecular mass of 9·3 kDa. This protein displays limited similarity to the VHv1.4 cysteine-rich protein from the PDV of Campoletis sonorensis, mostly within the signal peptide region. By using a TrV1-specific probe, the TrV1 gene was localized to segment G of the TrPDV genome. The cuticle and fat body were identified as the principal sites of TrV1 transcription, with little transcription observed in haemocytes and midgut. Western analysis of proteins extracted from selected tissues of parasitized insects suggested that the TrV1 protein is secreted in the haemolymph. As observed for other PDVs, injection of TrPDV did not suppress transcription of the gene that encodes juvenile hormone esterase, the activity of which is inhibited by the virus. We speculate that the TrV1 protein may play a role in the inhibition of C. fumiferana metamorphosis.

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