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 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 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 Transcriptional and translational responsiveness of the Neisseria gonorrhoeae type IV secretion system to conditions of host infections

2021 ◽  
Author(s):  
Melanie M. Callaghan ◽  
Amy K. Klimowicz ◽  
Abigail C. Shockey ◽  
John Kane ◽  
Caitlin S. Pepperell ◽  
...  
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Protein Levels ◽  
Type Iv ◽  
Coupling Protein ◽  
Host Infection ◽  
System Coupling ◽  
Translational Mechanisms

AbstractThe type IV secretion system of Neisseria gonorrhoeae translocates single-stranded DNA into the extracellular space, facilitating horizontal gene transfer and initiating biofilm formation. Expression of this system has been observed to be low under laboratory conditions, and multiple levels of regulation have been identified. We used a translational fusion of lacZ to traD, the gene for the type IV secretion system coupling protein, to screen for increased type IV secretion system expression. We identified several physiologically relevant conditions, including surface adherence, decreased manganese or iron, and increased zinc or copper, which increase gonococcal type IV secretion system protein levels through transcriptional and/or translational mechanisms. These metal treatments are reminiscent of the conditions in the macrophage phagosome. The ferric uptake regulator, Fur, was found to repress traD transcript levels, but to also have a second role, acting to allow TraD protein levels to increase only in the absence of iron. To better understand type IV secretion system regulation during infection, we examined transcriptomic data from active urethral infection samples from five men. These data demonstrated differential expression of 20 of 21 type IV secretion system genes during infection, indicating upregulation of genes necessary for DNA secretion during host infection.

Neisseria gonorrhoeaesecretes chromosomal DNA via a novel type IV secretion system

2005 ◽  
Vol 55 (6) ◽  
pp. 1704-1721 ◽  
Author(s):  
Holly L. Hamilton ◽  
Nadia M. Domínguez ◽  
Kevin J. Schwartz ◽  
Kathleen T. Hackett ◽  
Joseph P. Dillard
Keyword(s):  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Chromosomal Dna ◽  
Type Iv

scholarly journals Transcriptional and translational responsiveness of the Neisseria gonorrhoeae type IV secretion system to conditions of host infections

2021 ◽  
Author(s):  
Melanie M. Callaghan ◽  
Amy K. Klimowicz ◽  
Abigail C. Shockey ◽  
John Kane ◽  
Caitlin S. Pepperell ◽  
...  
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Protein Levels ◽  
Type Iv ◽  
Coupling Protein ◽  
Host Infection ◽  
System Coupling ◽  
Translational Mechanisms

The type IV secretion system of Neisseria gonorrhoeae translocates single-stranded DNA into the extracellular space, facilitating horizontal gene transfer and initiating biofilm formation. Expression of this system has been observed to be low under laboratory conditions, and multiple levels of regulation have been identified. We used a translational fusion of lacZ to traD , the gene for the type IV secretion system coupling protein, to screen for increased type IV secretion system expression. We identified several physiologically relevant conditions, including surface adherence, decreased manganese or iron, and increased zinc or copper, which increase gonococcal type IV secretion system protein levels through transcriptional and/or translational mechanisms. These metal treatments are reminiscent of the conditions in the macrophage phagosome. The ferric uptake regulator, Fur, was found to repress traD transcript levels, but to also have a second role, acting to allow TraD protein levels to increase only in the absence of iron. To better understand type IV secretion system regulation during infection, we examined transcriptomic data from active urethral infection samples from five men. These data demonstrated differential expression of 20 of 21 type IV secretion system genes during infection, indicating upregulation of genes necessary for DNA secretion during host infection.

High prevalence of functional type IV secretion system for CagA protein in Japanese clinical Helicobacter pylori

2001 ◽  
Vol 120 (5) ◽  
pp. A652-A653
Author(s):  
Y HIRATA ◽  
S MAEDA ◽  
Y MITUNO ◽  
M AKANUMA ◽  
T KAWABE ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Functional Type ◽  
Caga Protein ◽  
Type Iv ◽  
High Prevalence
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