scholarly journals Mating Pair Formation Homologue TraG Is a Variable Membrane Protein Essential for Contact-Independent Type IV Secretion of Chromosomal DNA by Neisseria gonorrhoeae

2013 ◽  
Vol 195 (8) ◽  
pp. 1666-1679 ◽  
Author(s):  
P. L. Kohler ◽  
Y. A. Chan ◽  
K. T. Hackett ◽  
N. Turner ◽  
H. L. Hamilton ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Neisseria Gonorrhoeae ◽  
Pair Formation ◽  
Type Iv Secretion ◽  
Mating Pair ◽  
Chromosomal Dna ◽  
Type Iv

scholarly journals Increased Expression of the Type IV Secretion System in Piliated Neisseria gonorrhoeae Variants

2010 ◽  
Vol 192 (7) ◽  
pp. 1912-1920 ◽  
Author(s):  
Wilmara Salgado-Pabón ◽  
Ying Du ◽  
Kathleen T. Hackett ◽  
Katelynn M. Lyons ◽  
Cindy Grove Arvidson ◽  
...  
Keyword(s):  
Growth Rate ◽  
Neisseria Gonorrhoeae ◽  
Antibiotic Resistance Genes ◽  
Gene Cassette ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Chromosomal Dna ◽  
Translational Machinery ◽  
Type Iv

ABSTRACT Neisseria gonorrhoeae produces a type IV secretion system that secretes chromosomal DNA. The secreted DNA is active in the transformation of other gonococci in the population and may act to transfer antibiotic resistance genes and variant alleles for surface antigens, as well as other genes. We observed that gonococcal variants that produced type IV pili secreted more DNA than variants that were nonpiliated, suggesting that the process may be regulated. Using microarray analysis, we found that a piliated strain showed increased expression of the gene for the putative type IV secretion coupling protein TraD, whereas a nonpiliated variant showed increased expression of genes for transcriptional and translational machinery, consistent with its higher growth rate compared to that of the piliated strain. These results suggested that type IV secretion might be controlled by either traD expression or growth rate. A mutant with a deletion in traD was found to be deficient in DNA secretion. Further mutation and complementation analysis indicated that traD is transcriptionally and translationally coupled to traI, which encodes the type IV secretion relaxase. We were able to increase DNA secretion in a nonpiliated strain by inserting a gene cassette with a strong promoter to drive the expression of the putative operon containing traI and traD. Together, these data suggest a model in which the type IV secretion system apparatus is made constitutively, while its activity is controlled through regulation of traD and traI.

scholarly journals Genetic and Sequence Analysis of the pTiC58 trb Locus, Encoding a Mating-Pair Formation System Related to Members of the Type IV Secretion Family

1998 ◽  
Vol 180 (23) ◽  
pp. 6164-6172 ◽  
Author(s):  
Pei-Li Li ◽  
Dawn M. Everhart ◽  
Stephen K. Farrand
Keyword(s):  
Sequence Analysis ◽  
Pair Formation ◽  
Type Iv Secretion ◽  
Ti Plasmid ◽  
Open Reading Frames ◽  
Conjugal Transfer ◽  
Mating Pair ◽  
Secretion Systems ◽  
Type Iv ◽  
And Function

ABSTRACT Conjugal transfer of pTiC58 requires two regions, trawhich contains the oriT and several genes involved in DNA processing and a region of undefined size and function that is located at the 2-o’clock position of the plasmid. Using transposon mutagenesis with Tn3HoHo1 and a binary transfer system, we delimited this second region, called trb, to an 11-kb interval between the loci for vegetative replication and nopaline catabolism. DNA sequence analysis of this region identified 13 significant open reading frames (ORFs) spanning 11,003 bp. The first, encodingtraI, already has been described and is responsible for the synthesis of Agrobacterium autoinducer (AAI) (I. Hwang, P.-L. Li, L. Zhang, K. R. Piper, D. M. Cook, M. E. Tate, and S. K. Farrand, Proc. Natl. Acad. Sci. USA 91:4639–4643, 1994). Translation products of the next 11 ORFs showed similarities to those of trbB, -C, -D,-E, -J, -K, -L,-F, -G, -H, and -I of the trb region of the octopine-type Ti plasmid pTi15955 and of the tra2 core region of RP4. In RP4, these genes encode mating-pair formation functions and are essential for the conjugal transfer of the IncP plasmid. Each of the trb gene homologues is oriented counterclockwise on the Ti plasmid. Expression of these genes, as measured by using the lacZ fusions formed by Tn3HoHo1, required the traI promoter and the transcriptional activator TraR along with its coinducer, AAI. While related to that of RP4, the trb system of pTiC58 did not allow propagation of the trb-specific bacteriophages PRD1, PRR1, and Pf3. The products of several trb genes of the Ti plasmid are similar to those of other loci that encode DNA transfer or protein secretion systems, all of which are members of the type IV secretion family.

scholarly journals A novel relaxase homologue is involved in chromosomal DNA processing for type IV secretion in Neisseria gonorrhoeae

2007 ◽  
Vol 66 (4) ◽  
pp. 930-947 ◽  
Author(s):  
Wilmara Salgado-Pabón ◽  
Samta Jain ◽  
Nicholas Turner ◽  
Chris van der Does ◽  
Joseph P. Dillard
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Type Iv Secretion ◽  
Chromosomal Dna ◽  
Type Iv ◽  
Dna Processing

scholarly journals Protein-Protein Interactions among Helicobacter pylori Cag Proteins

2006 ◽  
Vol 188 (13) ◽  
pp. 4787-4800 ◽  
Author(s):  
Valerie J. Busler ◽  
Victor J. Torres ◽  
Mark S. McClain ◽  
Oscar Tirado ◽  
David B. Friedman ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Protein Interactions ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Protein Protein Interactions ◽  
Chromosomal Dna ◽  
2D Dige ◽  
Type Iv ◽  
H Pylori

ABSTRACT Many Helicobacter pylori isolates contain a 40-kb region of chromosomal DNA known as the cag pathogenicity island (PAI). The risk for development of gastric cancer or peptic ulcer disease is higher among humans infected with cag PAI-positive H. pylori strains than among those infected with cag PAI-negative strains. The cag PAI encodes a type IV secretion system that translocates CagA into gastric epithelial cells. To identify Cag proteins that are expressed by H. pylori during growth in vitro, we compared the proteomes of a wild-type H. pylori strain and an isogenic cag PAI deletion mutant using two-dimensional difference gel electrophoresis (2D-DIGE) in multiple pH ranges. Seven Cag proteins were identified by this approach. We then used a yeast two-hybrid system to detect potential protein-protein interactions among 14 Cag proteins. One heterotypic interaction (CagY/7 with CagX/8) and two homotypic interactions (involving H. pylori VirB11/ATPase and Cag5) were similar to interactions previously reported to occur among homologous components of the Agrobacterium tumefaciens type IV secretion system. Other interactions involved Cag proteins that do not have known homologues in other bacterial species. Biochemical analysis confirmed selected interactions involving five of the proteins that were identified by 2D-DIGE. Protein-protein interactions among Cag proteins are likely to have an important role in the assembly of the H. pylori type IV secretion apparatus.

scholarly journals Type IV Secretion Machinery Promotes Ton-Independent Intracellular Survival of Neisseria gonorrhoeae within Cervical Epithelial Cells

2010 ◽  
Vol 78 (6) ◽  
pp. 2429-2437 ◽  
Author(s):  
Tracey A. Zola ◽  
Heather R. Strange ◽  
Nadia M. Dominguez ◽  
Joseph P. Dillard ◽  
Cynthia N. Cornelissen
Keyword(s):  
Epithelial Cells ◽  
Neisseria Gonorrhoeae ◽  
Host Cell ◽  
Iron Acquisition ◽  
Intracellular Survival ◽  
Type Iv Secretion ◽  
Open Reading Frames ◽  
Cell Infection ◽  
Type Iv ◽  
Cervical Epithelial Cells

ABSTRACT Survival of Neisseria gonorrhoeae within host epithelial cells is expected to be important in the pathogenesis of gonococcal disease. We previously demonstrated that strain FA1090 derives iron from a host cell in a process that requires the Ton complex and a putative TonB-dependent transporter, TdfF. FA1090, however, lacks the gonococcal genetic island (GGI) that is present in the majority of strains. The GGI in strain MS11 has been partially characterized, and it encodes a type IV secretion system (T4SS) involved in DNA release. In this study we investigated the role of iron acquisition and GGI-encoded gene products in gonococcal survival within cervical epithelial cells. We demonstrated that intracellular survival of MS11 was dependent on acquisition of iron from the host cell, but unlike the findings for FA1090, expression of the Ton complex was not required. Survival was not dependent on a putative TonB-like protein encoded in the GGI but instead was directly linked to T4SS structural components in a manner independent of the ability to release or internalize DNA. These data suggest that expression of selected GGI-encoded open reading frames confers an advantage during cervical cell infection. This study provides the first link between expression of the T4SS apparatus and intracellular survival of gonococci.

scholarly journals AtlA Functions as a Peptidoglycan Lytic Transglycosylase in the Neisseria gonorrhoeae Type IV Secretion System

2007 ◽  
Vol 189 (15) ◽  
pp. 5421-5428 ◽  
Author(s):  
Petra L. Kohler ◽  
Holly L. Hamilton ◽  
Karen Cloud-Hansen ◽  
Joseph P. Dillard
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Secretion Systems ◽  
Lytic Transglycosylases ◽  
Type Iv ◽  
Lytic Transglycosylase ◽  
Enzymatic Function ◽  
Type Iv Secretion Systems

ABSTRACT Type IV secretion systems require peptidoglycan lytic transglycosylases for efficient secretion, but the function of these enzymes is not clear. The type IV secretion system gene cluster of Neisseria gonorrhoeae encodes two peptidoglycan transglycosylase homologues. One, LtgX, is similar to peptidoglycan transglycosylases from other type IV secretion systems. The other, AtlA, is similar to endolysins from bacteriophages and is not similar to any described type IV secretion component. We characterized the enzymatic function of AtlA in order to examine its role in the type IV secretion system. Purified AtlA was found to degrade macromolecular peptidoglycan and to produce 1,6-anhydro peptidoglycan monomers, characteristic of lytic transglycosylase activity. We found that AtlA can functionally replace the lambda endolysin to lyse Escherichia coli. In contrast, a sensitive measure of lysis demonstrated that AtlA does not lyse gonococci expressing it or gonococci cocultured with an AtlA-expressing strain. The gonococcal type IV secretion system secretes DNA during growth. A deletion of ltgX or a substitution in the putative active site of AtlA severely decreased DNA secretion. These results indicate that AtlA and LtgX are actively involved in type IV secretion and that AtlA is not involved in lysis of gonococci to release DNA. This is the first demonstration that a type IV secretion peptidoglycanase has lytic transglycosylase activity. These data show that AtlA plays a role in type IV secretion of DNA that requires peptidoglycan breakdown without cell lysis.

scholarly journals Complete Nucleotide Sequence of the Conjugative Tetracycline Resistance Plasmid pFBAOT6, a Member of a Group of IncU Plasmids with Global Ubiquity

2004 ◽  
Vol 70 (12) ◽  
pp. 7497-7510 ◽  
Author(s):  
Glenn Rhodes ◽  
Julian Parkhill ◽  
Christine Bird ◽  
Kerrie Ambrose ◽  
Matthew C. Jones ◽  
...  
Keyword(s):  
Secretory Pathway ◽  
Transfer Functions ◽  
Genetic Load ◽  
Tetracycline Resistance ◽  
Complete Sequence ◽  
Pair Formation ◽  
Broad Host Range ◽  
Mating Pair ◽  
Associated Bacteria ◽  
Type Iv

ABSTRACT This study presents the first complete sequence of an IncU plasmid, pFBAOT6. This plasmid was originally isolated from a strain of Aeromonas caviae from hospital effluent (Westmorland General Hospital, Kendal, United Kingdom) in September 1997 (G. Rhodes, G. Huys, J. Swings, P. McGann, M. Hiney, P. Smith, and R. W. Pickup, Appl. Environ. Microbiol. 66:3883-3890, 2000) and belongs to a group of related plasmids with global ubiquity. pFBAOT6 is 84,748 bp long and has 94 predicted coding sequences, only 12 of which do not have a possible function that has been attributed. Putative replication, maintenance, and transfer functions have been identified and are located in a region in the first 31 kb of the plasmid. The replication region is poorly understood but exhibits some identity at the protein level with replication proteins from the gram-positive bacteria Bacillus and Clostridium. The mating pair formation system is a virB homologue, type IV secretory pathway that is similar in its structural organization to the mating pair formation systems of the related broad-host-range (BHR) environmental plasmids pIPO2, pXF51, and pSB102 from plant-associated bacteria. Partitioning and maintenance genes are homologues of genes in IncP plasmids. The DNA transfer genes and the putative oriT site also exhibit high levels of similarity with those of plasmids pIPO2, pXF51, and pSB102. The genetic load region encompasses 54 kb, comprises the resistance genes, and includes a class I integron, an IS630 relative, and other transposable elements in a 43-kb region that may be a novel Tn1721-flanked composite transposon. This region also contains 24 genes that exhibit the highest levels of identity to chromosomal genes of several plant-associated bacteria. The features of the backbone of pFBAOT6 that are shared with this newly defined group of environmental BHR plasmids suggest that pFBAOT6 may be a relative of this group, but a relative that was isolated from a clinical bacterial environment rather than a plant-associated bacterial environment.

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