Bacterial secretion systems are protein complexes present on the cell membranes of bacteria for secretion of substances. Specifically, they are the cellular devices used by pathogenic bacteria to secrete their virulence factors (mainly of proteins) to invade the host cells. They can be classified into different types based on their specific structure, composition and activity. Generally, proteins can be secreted through two different processes. One process is a one-step mechanism in which proteins from the cytoplasm of bacteria are transported and delivered directly through the cell membrane into the host cell. Another involves a two-step activity in which the proteins are first transported out of the inner cell membrane, then deposited in the periplasm, and finally through the outer cell membrane into the host cell.
These major differences can be distinguished between Gram-negative diderm bacteria and Gram-positive monoderm bacteria. But the classification is by no means clear and complete. There are at least eight types specific to Gram-negative bacteria, four to Gram-positive bacteria, while two are common to both. In addition, there is appreciable difference between diderm bacteria with lipopolysaccharide on the outer membrane (diderm-LPS) and those with mycolic acid (diderm-mycolate).
The export pathway is responsible for crossing the inner cell membrane in diderms, and the only cell membrane in monoderms.
Translocon
The general secretion (Sec) involves secretion of unfolded proteins that first remain inside the cells. In Gram-negative bacteria, the secreted protein is sent to either the inner membrane or the periplasm. But in Gram-positive bacteria, the protein can stay in the cell or is mostly transported out of the bacteria using other secretion systems. Among Gram-negative bacteria, Vibrio cholerae, Klebsiella pneumoniae, and Yersinia enterocolitica use the Sec system. Staphylococcus aureus and Listeria monocytogenes are Gram-positive bacteria that use the Sec system.
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The type III secretion system (T3SS or TTSS), also called the injectisome, is one of the bacterial secretion systems used by bacteria to secrete their effector proteins into the host's cells to promote virulence and colonisation. The T3SS is a needle-like protein complex found in several species of pathogenic gram-negative bacteria. The term Type III secretion system was coined in 1993. This secretion system is distinguished from at least five other secretion systems found in gram-negative bacteria.
Helicobacter pylori est une bactérie qui infecte la muqueuse gastrique. Sa structure externe est hélicoïdale (d'où son nom « Helicobacter »). Elle est munie de flagelles. 80 % des ulcères gastro-duodénaux sont causés par des infections de Helicobacter pylori, même si, chez beaucoup d'humains infectés, la maladie reste asymptomatique. Elle favorise de multiples maladies si elle reste dans l'estomac trop d'années. Helicobacter pylori est une bactérie très commune (trouvée chez 50 % des humains).
Bacterial secretion systems are protein complexes present on the cell membranes of bacteria for secretion of substances. Specifically, they are the cellular devices used by pathogenic bacteria to secrete their virulence factors (mainly of proteins) to invade the host cells. They can be classified into different types based on their specific structure, composition and activity. Generally, proteins can be secreted through two different processes.
Infectious diseases (ID) are still a major problem to human health. But how do pathogens make us sick? How do they evolve and spread? The discovery and use of antibiotics and vaccination has changed t
Tuberculosis (TB) is a chronic infectious disease that mainly affects the lungs and causes extensive human morbidity and mortality. It results from infection with Mycobacterium tuberculosis, a slow-gr
EPFL2018
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The ESX-1, type VII, secretion system represents the major virulence determinant of Mycobacterium tuberculosis, one of the most successful intracellular pathogens. Here, by combining genetic and high-
PUBLIC LIBRARY SCIENCE2018
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Pathogenicity of Mycobacterium tuberculosis (M. tb) is mediated by the ESX-1 secretion system, which exports EsxA and EsxB, the major virulence factors that are co-secreted with EspA and EspC. Functio