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Bacteria
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
Flagella are structures that produce locomotion or motility in those cells which possess them. Not all motile bacteria have flagella. There are other mechanisms of locomotion (e.g., gliding) in some organisms. Flagella are long hollow tubes composed of intertwined fibers of an alpha-helical form of the protein flagelin. These appendages emanate from the cytoplasmic membrane and are anchored by a specialized “hook” embedded in a basal body in the cell envelope. Some bacteria have a single flagellum (monotrichous, Figure 15.8); others have several flagella in a tuft at one location on the cell (lophotrichous); and others have flagella distributed about the entire cell (peritrichous). The arrangement is characteristic of the species and genus. Motility conferred by flagella is a result of their rotary motion; thereby giving directional propulsion to the cell, often in response to chemotactic stimuli.
Genetic Analysis of Sperm Motility
Published in Claude Gagnon, Controls of Sperm Motility, 2020
The t complex points out the utility of quantitative functional tests of flagellar movement to detect abnormal sperm movements not associated with any obvious ultrastructural defects. It may be a useful system in which to study the necessity of certain types of sperm movements for sperm transport and/or fertilization. There may be several loci within the t complex that affect flagellar function. Characterization of the products of these genes and their effects on flagella may lead to a better understanding of the control of flagellar movements in mammalian sperm.
Plesiomonas
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
Gabriel Forn-Cuní, Zoha Tavakkoliamol, Juan M. Tomás
The exact mechanism of P. shigelloides infection is currently unknown, in part due to the lack of effective infection models. However, several virulence factors have been associated with infections, including flagella motility, the LPS complex, enterotoxins, β-hemolysins, and plasmids.
Mapping the human sperm proteome – novel insights into reproductive research
Published in Expert Review of Proteomics, 2023
Mika Alexia Miyazaki, Raquel Lozano Guilharducci, Paula Intasqui, Ricardo Pimenta Bertolla
During sperm passage through the female reproductive tract, in order for successful fertilization to occur, spermatozoa undergo a series of successive events, such as capacitation, hyperactivation, penetration through the cumulus cells and zona pellucida, and membrane fusion [6]. Sperm proteins play a key role in these events, participating in molecular pathways related to capacitation [7], motility [8] and triggering acrosome reaction, allowing access to the oocyte membrane [9]. Therefore, deletion or absence of some sperm proteins may cause male infertility. For example, the sperm flagellum is composed of several proteins that promote flagellar motility. Miki and colleagues [10] demonstrated that A-kinase anchor protein 4 (AKAP4) is an important protein composing the flagellum fibrous sheath, and its absence is related to immobile cells and asthenozoospermia, which in turn negatively affects the success of assisted reproduction techniques, fertilization rates, and pregnancy outcomes [11–17]
Regulation of flagellar motility and biosynthesis in enterohemorrhagic Escherichia coli O157:H7
Published in Gut Microbes, 2022
Hongmin Sun, Min Wang, Yutao Liu, Pan Wu, Ting Yao, Wen Yang, Qian Yang, Jun Yan, Bin Yang
The bacterial flagellum is a macromolecular machine that consists of a basal body (rotary motor), a hook (universal joint), and a filament (propeller).8 Flagellar-mediated motility confers an important advantage for bacteria in moving toward favorable conditions or in avoiding detrimental environments and allows bacteria to pursue nutrients and to reach and maintain their preferred niches for survival.9 In addition to having locomotive properties, flagellum-mediated motility plays diverse roles in the pathogenesis and progression of EHEC O157:H7 infection. Upon entering the host intestine, EHEC O157:H7 relies on flagellum-mediated motility to reach and adhere to optimal colonization sites in the host.10 Subsequently, EHEC O157:H7 inhibits flagellar biosynthesis to save energy and minimize host immunity (Figure 1).10
Pathobionts: mechanisms of survival, expansion, and interaction with host with a focus on Clostridioides difficile
Published in Gut Microbes, 2021
Harish Chandra, Krishna Kant Sharma, Olli H. Tuovinen, Xingmin Sun, Pratyoosh Shukla
Adhesion to the mucosal surfaces through the expression of flagellar proteins in pathobionts provides another opportunity for colonization and pathogenicity. The C. difficile flagellar proteins flagellin and flagella cap protein encoded by the fliC and fliD genes, respectively, have been implicated in C. difficile colonization and pathogenicity by adherence to the mucus in a murine study.59 Mutant strains that lack flagella components have been implicated in poor adherence to mucus and manifestation of low virulence. In this regard, c-diGMP has been shown to play a vital role in flagellar expression, biofilm formation, and adhesion.62 Elevated levels of c-diGMPs have been reported to downregulate flagellar expression and inhibit toxin synthesis and motility via binding to riboswitch upstream of the flgB operon.62 Additionally, c-diGMP induces the expression of type IV pili that interact with intestinal epithelium cells that facilitate the biofilm formation.63 There are other virulence proteins (Spo0A,Cwp66, Cwp84, S-layer protein A, and adhesin fibronectin-binding protein A) that facilitate C. difficile adhesion and biofilm formation.64 Therefore, upon selection and expansion, the pathobiont can use various tactics such as toxins, cell wall proteins, and flagellar proteins to disrupt the host intestinal barrier, leading to severe colitis in the host.