MotA (PA4954) is the A subunit of the MotAB flagellar stator of Pseudomonas aeruginosa. It is a polytopic inner-membrane protein (four predicted transmembrane helices) of the MotA/TolQ/ExbB family and, with MotB (PA4953), forms an ion-conducting stator unit whose cytoplasmic loop engages the rotor protein FliG to generate torque. P. aeruginosa has a second stator, MotCD (PA1460-PA1461); the two are largely redundant for swimming, and loss of both MotA homologues abolishes motility. MotCD is the stator needed for swarming on firmer surfaces, whereas MotAB is dispensable for swarming and, at high c-di-GMP, is needed for repression of swarming, probably by displacing MotCD from the motor.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005886 plasma membrane | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular-location mapping (inner membrane); the UniProt location line itself is ARBA-predicted. Reason: MotA has four predicted transmembrane helices and belongs to the MotA family; stator units are integral inner-membrane complexes. The TM prediction and the stator role agree with the location. Supporting Evidence: file:PSEAE/motA/motA-uniprot.txt TRANSMEM 7..29 PMID:15629949 the stator (the stationary component of the motor within which the rotor turns), which is composed of two integral membrane proteins, MotA and MotB |
| GO:0006935 chemotaxis | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: InterPro2GO mapping from the MotA-like family signature. Reason: The stator generates torque; it is the output of chemotaxis signalling, not part of it (switching is set by CheY-P binding at the FliM/FliN switch). In P. aeruginosa, stator mutants that remain motile show normal chemotaxis. Chemotaxis is an indirect consequence of motor function, as for any flagellar structural protein. Supporting Evidence: PMID:15375113 Therefore, the radial expansion defect observed for motAB strains in semisolid motility agar cannot be attributed to polar effects that disturb chemotaxis. |
| GO:0071973 bacterial-type flagellum-dependent cell motility | IMP PMID:15375113 The complex flagellar torque generator of Pseudomonas aerugi... | ACCEPT | Summary: Doyle et al. 2004 (who call PA4954-PA4953 "motCD", the reverse of current usage): insertions in PA4954 reduce motility, and loss of both MotA homologues abolishes it. Reason: Core process. MotA is a stator subunit and does part of the work of flagellar rotation. The single mutant has a partial defect (lower swimming speed and radial expansion) and the double MotA-homologue mutant is non-motile, which fits a stator shared with a paralogue. Supporting Evidence: PMID:15375113 Thus, the motCD locus contributes to, but is not exclusively responsible for, motor function. PMID:15375113 Mutation of both genes encoding the MotA homologs or MotB homologs was sufficient to abolish motility. |
| GO:0071978 bacterial-type flagellum-dependent swarming motility | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: PAINT IBA from PTN001252377 (MotA clade), seeded by the PseudoCAP IMP swarming rows on MotA (PA4954, this protein) and MotC (PA1460). Reason: For P. aeruginosa MotA the term is a defensible context statement (MotAB alone supports swarming on soft agar), but swarming is not the core role of this stator. The self-reference in WITH/FROM is the expected mark of a seed. The node term is too specific for the clade (Aquifex, Thermotoga, Helicobacter, Leptospira and Planctomycete stator proteins among the 29 leaves); the node-level GO_CENTRAL defect is recorded once, on motC (genes/PSEAE/motC), the seed with the direct single-mutant swarming phenotype. Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH CONTEXT OR TISSUE MISMATCH Sources checked: PANTHER:PTN001252377 Β· PTN001252377 SOURCE WEAK OR INFERRED PAINT leaf GAF (cached) lists 29 GO:0071978 leaves in 19 taxa, including Aquifex, Thermotoga, Helicobacter, Leptospira, Clostridium, Bacillus and Rhodopirellula stators for which no swarming data are given; flagellar rotation is the shared role. UniProtKB:G3XD73 Β· motC (PA1460) SUPPORTS SOURCE BUT NOT TARGET Sound seed; the motCD single mutant fails to swarm on 0.5% agar or firmer. The IBD stands on this seed for P. aeruginosa. UniProtKB:Q9HUL1 Β· motA (self) SOURCE WEAK OR INFERRED Expected self-seed. The IMP rows rest on the double stator mutant (PMID:15629949) and on a hyperswarming phenotype (PMID:25349157). Supporting Evidence: PMID:15629949 The fact that the motCD mutant, but not the motAB mutant, has a phenotype with respect to swarming suggests that these two stators may have different roles in swarming motility. |
| GO:0071978 bacterial-type flagellum-dependent swarming motility | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: InterPro2GO mapping from the MotA-like family signature. Reason: Same claim as the IBA and IMP rows; for MotAB swarming is a context in which the stator can act, not its core role. A family-wide mapping to swarming is over-specific for the same reasons as the PTN001252377 IBD. Supporting Evidence: PMID:15629949 we conclude that the MotAB and MotBC proteins are stators that play a role in flagellar motor function for both swimming and swarming motility. |
| GO:0071978 bacterial-type flagellum-dependent swarming motility | IMP PMID:15629949 Evidence for two flagellar stators and their role in the mot... | KEEP AS NON CORE | Summary: PseudoCAP IMP from Toutain et al. 2005 (PA14). The motAB deletion swarms like wild type; the motAB motCD double deletion does not swarm. Reason: The authors conclude both stators act in swarming, and MotAB alone (in the motCD mutant) supports swarming on 0.45% agar, so the stator does take part in the swarming motor. But the single-gene phenotype is wild type, MotCD is the stator swarming depends on, and multicopy MotAB inhibits swarming. Context-specific and non-core; the evidence is a genetic interaction rather than a motA mutant phenotype. Supporting Evidence: PMID:15629949 we conclude that the MotAB and MotBC proteins are stators that play a role in flagellar motor function for both swimming and swarming motility. PMID:15629949 The double mutant Ξ motAB Ξ motCD is not able to swarm under any of the conditions tested. |
| GO:0071978 bacterial-type flagellum-dependent swarming motility | IMP PMID:25349157 Cyclic di-GMP-mediated repression of swarming motility by Ps... | KEEP AS NON CORE | Summary: PseudoCAP IMP from Kuchma et al. 2015 (PA14; abstract only): mutating motAB increases swarming and relieves c-di-GMP repression of swarming, while MotA overexpression represses swarming. Reason: The stator is physically part of the motor during swarming, so a context-specific involved_in is not false (and is supported by PMID:15629949); but the phenotype reported here is the opposite of a requirement (the mutant swarms more), and the paper's finding is that MotAB is needed for c-di-GMP-mediated repression of swarming. Full text was not retrievable, so the row is kept, consistent with the other swarming rows; see the PSEUDOCAP defect. Supporting Evidence: PMID:25349157 Here we show that the repression of swarming motility requires a functional MotAB stator complex. |
| GO:0120101 bacterial-type flagellum stator complex | IBA GO_REF:0000033 | ACCEPT | Summary: PAINT IBA from PTN001252377, seeded by E. coli MotA (P09348). Reason: Core location. PA4954 is the P. aeruginosa MotA most similar to the enteric MotA proteins and is described experimentally as part of one of the two stator complexes of the polar flagellum. Supporting Evidence: PMID:25349157 P. aeruginosa encodes two stator complexes, MotAB and MotCD, that participate in the function of its single polar flagellum. PMID:15629949 One pair of proteins was designated MotAB (PA4954-4953) based on the current annotation of the P. aeruginosa PAO1 genome and on the sequence similarity of the P. aeruginosa PA4954-4953 proteins to the well-characterized E. coli stator proteins MotAB |
Loading supporting contentβ¦
Download this section (compressed HTML)Q: Does MotAB restrain swarming by occupying stator sites on the motor (displacing MotCD), or does its interaction with FliG change torque output on surfaces?
Experiment: Measure stator occupancy (MotA- and MotC-fluorescent fusions per motor) and single-motor torque in cells on swarm agar at low and high c-di-GMP, including MotA FliG-interface point mutants, to test the stator-exchange model.
Loading supporting contentβ¦
Download this section (compressed HTML)Loading supporting contentβ¦
Download this section (compressed HTML)