Gene Ontology annotation through association of InterPro records with GO terms
Gene Ontology annotation based on Enzyme Commission mapping
Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity
Annotation inferences using phylogenetic trees
Automatic assignment of GO terms using logical inference, based on on inter-ontology links
Combined Automated Annotation using Multiple IEA Methods
Functional characterization of the type III secretion ATPase SsaN encoded by Salmonella pathogenicity island 2.
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Purified SsaN hydrolyses ATP (Km 0.81 mM, 0.36 umol/min/mg) with non-linear dependence on protein concentration; the DCCD-box variant R192G has no detectable activity.
"Purified SsaN-Myc-His6 hydrolyzed ATP in a linear, time-dependent manner with a mean ATPase activity of 0.36"
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An ssaN deletion cannot secrete the translocator SseB or the effector SseJ; complementation restores secretion, R192G does not.
"SseB secretion from the ssaN mutant strain was undetectable"
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SsaN forms a C-ring/sorting-platform complex with SsaK (SctL2) and SsaQ, and binds the SPI-2 chaperones SsaE, SseA, SscA and SscB.
"SsaN interacted with SsaK and SsaQ to form the C ring complex"
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SsaN releases the translocator SseB from its chaperone SsaE in an ATP-dependent manner; ATPgammaS and R192G do not support release.
"our results indicate that SsaN releases the translocator protein SseB from the T3SS-2 specific chaperone SsaE in an ATP-dependent manner"
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SsaN is in both the soluble and the membrane fraction of Salmonella grown under SPI-2-inducing conditions, independently of SsaK and SsaQ.
"These results indicated that SsaN could associate with the membrane regardless of the presence of the other ATPase-associated components."
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An ssaN mutant is strongly attenuated in mixed mouse infection (CI 0.047), restored by complementation.
"The CI value of the wild-type strain versus the ssaN mutant strain was significantly reduced to 0.047"
Identification of the docking site between a type III secretion system ATPase and a chaperone for effector cargo.
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2.1 A crystal structure of SsaN (PDB 4NPH); the C-terminal region forms the docking site for the multicargo chaperone SrcA, and docking-site mutants that retain ATPase activity are attenuated in vivo.
"The C-terminal region of T3SS ATPases mediates binding with multiple contact points along the chaperone."
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SsaN is required for secretion of SPI-2-encoded needle and translocon components; some effectors encoded outside SPI-2 can be rerouted via T3SS-1.
"As expected, SsaN was required for the secretion of needle and translocon components"
Enzymatic characterization of FliI. An ATPase involved in flagellar assembly in Salmonella typhimurium.
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The flagellar family member FliI is a Mg2+-dependent ATPase insensitive to F-, V- and P-type ATPase inhibitors, i.e. it is not a rotary proton pump.
"The activity was not affected by inhibitors of the F-, V- or P-type ATPases"
Fueling type III secretion.
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The proton motive force is the primary energy source for type III secretion, and its conversion to export occurs at the inner-membrane export gate (FlhA/YscV with FliJ/YscO), not at the ATPase.
"conversion of the pmf to protein export is the rate limiting step for protein export via the T3SS, and the pmf therefore the primary fuel for secretion via the T3SS"
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Collapsing the pmf blocks type III protein export.
"Collapsing the pmf abolishes protein export via T3SS."
Falcon deep research report for Salmonella SctN2/SsaN
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SsaN has no transmembrane helices; its membrane-fraction signal reflects peripheral association with the cytoplasmic face of the SPI-2 apparatus.
"SsaN lacks transmembrane helices and is not classified as an integral membrane protein"
Curation notes for Salmonella SctN2/SsaN
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PANTHER node PTN008558586 is a duplication node whose children separate the F1-beta subfamilies (PTN008558588) from the bacterial export ATPases (PTN000390097, containing PTHR15184:SF62, this protein). All IBD seeds lie in the F1-beta child.
"the IBD sits *on* the duplication node that separated F1-beta from the export ATPases"