Structural highlights
Function[PILQ_PSEAE] Essential for the formation of pili. Involved in the biogenesis of type 4 fimbriae probably by serving as a 'porthole' allowing passage of the fimbrae through the outer membrane. Publication Abstract from PubMedThe type IV pilus machinery is a multi-protein complex that polymerizes and depolymerizes a pilus fiber used for attachment, twitching motility, phage adsorption, natural competence, protein secretion, and surface-sensing. An outer membrane secretin pore is required for passage of the pilus fiber out of the cell. Herein, the structure of the tetradecameric secretin, PilQ, from the Pseudomonas aeruginosa type IVa pilus system was determined to 4.3 A and 4.4 A resolution in the presence and absence of C7 symmetric spikes, respectively. The heptameric spikes were found to be two tandem C-terminal domains of TsaP. TsaP forms a belt around PilQ and while it is not essential for twitching motility, overexpression of TsaP triggers a signal cascade upstream of PilY1 leading to cyclic di-GMP up-regulation. These results resolve the identity of the spikes identified with Proteobacterial PilQ homologs and may reveal a new component of the surface-sensing cyclic di-GMP signal cascade. CryoEM map of Pseudomonas aeruginosa PilQ enables structural characterization of TsaP.,McCallum M, Tammam S, Rubinstein JL, Burrows LL, Howell PL Structure. 2020 Dec 11. pii: S0969-2126(20)30466-4. doi:, 10.1016/j.str.2020.11.019. PMID:33338410[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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