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International Journal of Molecular... Dec 2023Bacteria have existed on Earth for billions of years, exhibiting ubiquity and involvement in various biological activities. To ensure survival, bacteria usually release... (Review)
Review
Bacteria have existed on Earth for billions of years, exhibiting ubiquity and involvement in various biological activities. To ensure survival, bacteria usually release and secrete effector proteins to acquire nutrients and compete with other microorganisms for living space during long-term evolution. Consequently, bacteria have developed a range of secretion systems, which are complex macromolecular transport machines responsible for transporting proteins across the bacterial cell membranes. Among them, one particular secretion system that stands out from the rest is the type V secretion system (T5SS), known as the "autotransporter". Bacterial activities mediated by T5SS include adherence to host cells or the extracellular matrix, invasion of host cells, immune evasion and serum resistance, contact-dependent growth inhibition, cytotoxicity, intracellular flow, protease activity, autoaggregation, and biofilm formation. In a bacterial body, it is not enough to rely on T5SS alone; in most cases, T5SS cooperates with other secretion systems to carry out bacterial life activities, but regardless of how good the relationship is, there is friction between the secretion systems. T5SS and T1SS/T2SS/T3SS/T6SS all play a synergistic role in the pathogenic processes of bacteria, such as nutrient acquisition, pathogenicity enhancement, and immune modulation, but T5SS indirectly inhibits the function of T4SS. This could be considered a love-hate relationship between secretion systems. This paper uses the systematic literature review methodology to review 117 journal articles published within the period from 1995 to 2024, which are all available from the PubMed, Web of Science, and Scopus databases and aim to elucidate the link between T5SS and other secretion systems, providing clues for future prevention and control of bacterial diseases.
Topics: Type V Secretion Systems; Bacteria; Bodily Secretions; Cell Aggregation; Cell Membrane
PubMed: 38203452
DOI: 10.3390/ijms25010281 -
Current Protein & Peptide Science 2017Protein is an important yet the most expensive dietary component for farm ruminant animals. Understanding the mechanism behind protein utilization in animals for... (Review)
Review
Protein is an important yet the most expensive dietary component for farm ruminant animals. Understanding the mechanism behind protein utilization in animals for maintenance and milk production is critical for raising animals efficiently. Once the protein has been ingested, it undergoes various transformations in the gut before it is absorbed into blood and its precursors are harnessed by the mammary gland for milk protein synthesis in lactating animals. Several signaling pathways are involved both in absorption and in milk protein biosynthesis. Protein metabolism and signal pathway regulation in various tissues of ruminant are thus reviewed with emphasis on two particular tissues, the rumen and the mammary gland.
Topics: Amino Acids; Animals; Female; Humans; Lactation; Mammary Glands, Human; Milk; Milk Proteins; Protein Biosynthesis; Proteins; Proteolysis; Rumen; Ruminants; Signal Transduction
PubMed: 27356938
DOI: 10.2174/1389203717666160627075021 -
Microbiology Spectrum Mar 2019Type I secretion systems (T1SS) are widespread in Gram-negative bacteria, especially in pathogenic bacteria, and they secrete adhesins, iron-scavenger proteins, lipases,... (Review)
Review
Type I secretion systems (T1SS) are widespread in Gram-negative bacteria, especially in pathogenic bacteria, and they secrete adhesins, iron-scavenger proteins, lipases, proteases, or pore-forming toxins in the unfolded state in one step across two membranes without any periplasmic intermediate into the extracellular space. The substrates of T1SS are in general characterized by a C-terminal secretion sequence and nonapeptide repeats, so-called GG repeats, located N terminal to the secretion sequence. These GG repeats bind Ca ions in the extracellular space, which triggers folding of the entire protein. Here we summarize our current knowledge of how Gram-negative bacteria secrete these substrates, which can possess a molecular mass of up to 1,500 kDa. We also describe recent findings that demonstrate that the absence of periplasmic intermediates, the "classic" mode of action, does not hold true for all T1SS and that we are beginning to realize modifications of a common theme.
Topics: Bacterial Proteins; Bacterial Secretion Systems; Biological Transport; Gram-Negative Bacteria; Protein Transport; Type I Secretion Systems
PubMed: 30848237
DOI: 10.1128/microbiolspec.PSIB-0003-2018 -
Biochemical Society Transactions Aug 2014The efficient folding, assembly and secretion of proteins from mammalian cells is a critically important process for normal cell physiology. Breakdown of the ability of... (Review)
Review
The efficient folding, assembly and secretion of proteins from mammalian cells is a critically important process for normal cell physiology. Breakdown of the ability of cells to secrete functional proteins leads to disease pathologies caused by a lack of protein function or by cell death resulting from an aggravated stress response. Central to the folding of secreted proteins is the formation of disulfides which both aid folding and provide stability to the protein structure. For disulfides to form correctly necessitates the appropriate redox environment within the endoplasmic reticulum: too reducing and disulfides will not form, too oxidizing and non-native disulfides will not be resolved. How the endoplasmic reticulum maintains the correct redox balance is unknown. Although we have a good appreciation of the processes leading to a more oxidizing environment, our understanding of how any counterbalancing reductive pathway operates is limited. The present review looks at potential mechanisms for introducing reducing equivalents into the endoplasmic reticulum and discusses an approach to test these hypotheses.
Topics: Animals; Endoplasmic Reticulum; Humans; Oxidation-Reduction; Protein Folding; Proteins
PubMed: 25109977
DOI: 10.1042/BST20140065 -
Journal of Microbiology and... May 2021is the most abundant genus in the fungal microflora found on human skin, and it is associated with various skin diseases. Among the 18 different species of that have... (Review)
Review
is the most abundant genus in the fungal microflora found on human skin, and it is associated with various skin diseases. Among the 18 different species of that have been identified to date, and are the most predominant fungal species found on human skin. Several studies have suggested a possible link between and skin disorders. However, our knowledge on the physiology and pathogenesis of in human body is still limited. is unable to synthesize fatty acids; hence, it uptakes external fatty acids as a nutrient source for survival, a characteristic compensated by the secretion of lipases and degradation of sebum to produce and uptake external fatty acids. Although it has been reported that the activity of secreted lipases may contribute to pathogenesis of , majority of the data were indirect evidences; therefore, enzymes' role in the pathogenesis of infections is still largely unknown. This review focuses on the recent advances on in the context of an emerging interest for lipases and summarizes the existing knowledge on , diseases associated with the fungus, and the role of the reported lipases in its physiology and pathogenesis.
Topics: Dermatomycoses; Fungal Proteins; Humans; Lipase; Lipid Metabolism; Malassezia; Sebum; Skin; Virulence
PubMed: 33526754
DOI: 10.4014/jmb.2012.12048 -
Science Signaling Aug 2020The oral bacterium is often found in colorectal cancer (CRC). In the 21 July 2020 issue of , Casasanta show that CRC cell-resident promotes cytokine secretion that... (Review)
Review
The oral bacterium is often found in colorectal cancer (CRC). In the 21 July 2020 issue of , Casasanta show that CRC cell-resident promotes cytokine secretion that may potentiate tumor growth and metastatic progression in patients.
Topics: Bodily Secretions; Cell Movement; Chemokine CXCL1; Colorectal Neoplasms; Fusobacterium nucleatum; Humans; Interleukin-8
PubMed: 32788340
DOI: 10.1126/scisignal.abc4218 -
Frontiers in Cellular and Infection... 2023Many pathogens use Type III and Type IV protein secretion systems to secrete virulence factors from the bacterial cytosol into host cells. These systems operate through... (Review)
Review
Many pathogens use Type III and Type IV protein secretion systems to secrete virulence factors from the bacterial cytosol into host cells. These systems operate through a one-step mechanism. The secreted substrates (protein or nucleo-protein complexes in the case of Type IV conjugative systems) are guided to the base of the secretion channel, where they are directly delivered into the host cell in an ATP-dependent unfolded state. Despite the numerous disparities between these secretion systems, here we have focused on the structural and functional similarities between both systems. In particular, on the structural similarity shared by one of the main ATPases (EscN and VirD4 in Type III and Type IV secretion systems, respectively). Interestingly, these ATPases also exhibit a structural resemblance to F-ATPases, which suggests a common mechanism for substrate secretion. The correlation between structure and function of essential components in both systems can provide significant insights into the molecular mechanisms involved. This approach is of great interest in the pursuit of identifying inhibitors that can effectively target these systems.
Topics: Type IV Secretion Systems; Bacterial Proteins; Bacteria; Protein Transport; Adenosine Triphosphatases; Type III Secretion Systems
PubMed: 38089815
DOI: 10.3389/fcimb.2023.1255852 -
Current Opinion in Structural Biology Apr 2023Contrary to first appearances, mucus structural biology is not an oxymoron. Though mucus hydrogels derive their characteristics largely from intrinsically disordered,... (Review)
Review
Contrary to first appearances, mucus structural biology is not an oxymoron. Though mucus hydrogels derive their characteristics largely from intrinsically disordered, heavily glycosylated polypeptide segments, the secreted mucin glycoproteins that constitute mucus undergo an orderly assembly process controlled by folded domains at their termini. Recent structural studies revealed how mucin complexes promote disulphide-mediated polymerization to produce the mucus gel scaffold. Additional protein-protein and protein-glycan interactions likely tune the mesoscale properties, stability, and activities of mucins. Evidence is emerging that even intrinsically disordered glycosylated segments have specific structural roles in the production and properties of mucus. Though soft-matter biophysical approaches to understanding mucus remain highly relevant, high-resolution structural studies of mucins and other mucus components are providing new perspectives on these vital, protective hydrogels.
Topics: Mucins; Mucus; Glycoproteins; Polysaccharides; Glycosylation
PubMed: 36753925
DOI: 10.1016/j.sbi.2022.102524 -
Domestic Animal Endocrinology Jan 2016Insulin is the primary acute anabolic coordinator of nutrient partitioning. Hyperglycemia is the main stimulant of insulin secretion, but other nutrients such as... (Review)
Review
Insulin is the primary acute anabolic coordinator of nutrient partitioning. Hyperglycemia is the main stimulant of insulin secretion, but other nutrients such as specific amino acids, fatty acids, and ketoacids can potentiate pancreatic insulin release. Incretins are intestinal hormones with insulinotropic activity and are secreted in response to food ingestion, thus integrating diet chemical composition with the regulation of insulin release. In addition, prolactin is required for proper islet development, and it stimulates β-cell proliferation. Counterintuitively, bacterial components appear to signal insulin secretion. In vivo lipopolysaccharide infusion acutely increases circulating insulin, which is paradoxical as endotoxemia is a potent catabolic condition. Insulin is a potent anabolic orchestrator of nutrient partitioning, and this is particularly true in adipocytes. Insulin dictates lipid accretion in a dose-dependent manner during preadipocyte development in adipose tissue-derived stromal vascular cell culture. However, in vivo studies focused on insulin's role in regulating adipose tissue metabolism from growing, and market weight pigs are sometimes inconsistent, and this variability appears to be animal, age and depot dependent. Additionally, porcine adipose tissue synthesizes and secretes a number of adipokines (leptin, adiponectin, and so forth) that directly or indirectly influence insulin action. Therefore, because insulin has an enormous impact on agriculturally important phenotypes, it is critical to have a better understanding of how insulin homeostasis is governed.
Topics: Adipocytes; Adipokines; Adipose Tissue; Agriculture; Animals; Cattle; Embryonic Development; Homeostasis; Incretins; Insulin; Insulin Secretion; Insulin-Secreting Cells; Leptin; Lipogenesis; Lipolysis; Prolactin; Swine
PubMed: 26521203
DOI: 10.1016/j.domaniend.2015.07.001 -
Nutrients Mar 2021The gastrointestinal tract can assess the nutrient composition of ingested food. The nutrient-sensing mechanisms in specialised epithelial cells lining the... (Review)
Review
The gastrointestinal tract can assess the nutrient composition of ingested food. The nutrient-sensing mechanisms in specialised epithelial cells lining the gastrointestinal tract, the enteroendocrine cells, trigger the release of gut hormones that provide important local and central feedback signals to regulate nutrient utilisation and feeding behaviour. The evidence for nutrient-stimulated secretion of two of the most studied gut hormones, glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), along with the known cellular mechanisms in enteroendocrine cells recruited by nutrients, will be the focus of this review. The mechanisms involved range from electrogenic transporters, ion channel modulation and nutrient-activated G-protein coupled receptors that converge on the release machinery controlling hormone secretion. Elucidation of these mechanisms will provide much needed insight into postprandial physiology and identify tractable dietary approaches to potentially manage nutrition and satiety by altering the secreted gut hormone profile.
Topics: Bodily Secretions; Enteroendocrine Cells; Gastric Inhibitory Polypeptide; Gastrointestinal Hormones; Gastrointestinal Tract; Glucagon-Like Peptide 1; Humans; Nutritional Physiological Phenomena; Postprandial Period
PubMed: 33803183
DOI: 10.3390/nu13030883