The atypical hybrid histidine protein kinase RodK in Myxococcus xanthus: spatial proximity supersedes kinetic preference in phosphotransfer reactions.
Many proteins of two-component signal transduction systems (TCS) have domain structures that do not comply with a phosphate flow as observed in linear TCS, phosphorelays, or simple branched pathways. An example is RodK, which is essential for fruiting body formation in Myxococcus xanthus and, in addition to a sensor domain, consists of a kinase domain and three receiver domains (RodK-R1, -R2, and -R3), all of which are functionally important. We identified the RokA response regulator as part of the RodK pathway. In vitro the isolated RodK kinase domain engages in phosphotransfer to RodK-R3 and RokA, with a kinetic preference for RokA. However, in the context of the full-length protein, the RodK kinase domain has a preference for phosphotransfer to RodK-R3 over RokA. We suggest that in full-length RodK, the spatial proximity of the RodK kinase domain and RodK-R3 compensate for the kinetic preference of the isolated kinase domain for RokA. Thus, the kinetic preference observed using an isolated kinase domain of a hybrid kinase does not necessarily reflect the phosphotransfer preference of the full-length protein. We speculate that the phosphorylation status of RodK-R1 and RodK-R2 determines whether RodK engages in phosphotransfer to RodK-R3 or RokA in vivo.
Wegener-Feldbrügge
Sigrun
S
Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Str., 35043 Marburg, Germany.
Søgaard-Andersen
Lotte
L
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D000071677:Histidine Kinase; D007700:Kinetics; D008969:Molecular Sequence Data; D016941:Myxococcus xanthus / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D010766:Phosphorylation; D011494:Protein Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
D001426:Bacterial Proteins; D011494:Protein Kinases; D000071677:Histidine Kinase