The small GTPase MglA together with the TPR domain protein SgmX stimulates type IV pili formation in M. xanthus
Autor: | Luis António Menezes Carreira, Lotte Søgaard-Andersen, Anna Potapova |
---|---|
Rok vydání: | 2020 |
Předmět: |
GTPase-activating protein
bacterial motility Protein domain GTPase Microbiology Pilus PilB ATPase 03 medical and health sciences Bacterial Proteins MglA GTPase Tetratricopeptide Repeat Small GTPase Myxococcus xanthus 030304 developmental biology 0303 health sciences Multidisciplinary Polarity (international relations) type IV pili biology 030306 microbiology Chemistry Cell Polarity Biological Sciences biology.organism_classification Cell biology Tetratricopeptide Fimbriae Bacterial Fimbriae Proteins bacterial polarity |
Zdroj: | Proceedings of the National Academy of Sciences of the United States of America |
ISSN: | 1091-6490 0027-8424 |
DOI: | 10.1073/pnas.2004722117 |
Popis: | Significance Many bacteria move across surfaces using type IV pili (T4P). The piliation pattern varies between species; however, the underlying mechanisms governing these patterns remain largely unknown. Here, we demonstrate that in the rod-shaped Myxococcus xanthus cells, the unipolar formation of T4P at the leading cell pole is the result of stimulation by the small GTPase MglA together with the effector protein SgmX, while MglB, the cognate MglA GTPase activating protein (GAP) that localizes to the lagging cell pole, blocks this stimulation at the lagging pole due to its GAP activity. During reversals, MglA/SgmX and MglB switch polarity, laying the foundation for T4P formation at the new leading cell pole and inhibition of T4P formation at the former leading cell pole. Bacteria can move across surfaces using type IV pili (T4P), which undergo cycles of extension, adhesion, and retraction. The T4P localization pattern varies between species; however, the underlying mechanisms are largely unknown. In the rod-shaped Myxococcus xanthus cells, T4P localize at the leading cell pole. As cells reverse their direction of movement, T4P are disassembled at the old leading pole and then form at the new leading pole. Thus, cells can form T4P at both poles but engage only one pole at a time in T4P formation. Here, we address how this T4P unipolarity is realized. We demonstrate that the small Ras-like GTPase MglA stimulates T4P formation in its GTP-bound state by direct interaction with the tetratricopeptide repeat (TPR) domain-containing protein SgmX. SgmX, in turn, is important for polar localization of the T4P extension ATPase PilB. The cognate MglA GTPase activating protein (GAP) MglB, which localizes mainly to the lagging cell pole, indirectly blocks T4P formation at this pole by stimulating the conversion of MglA-GTP to MglA-GDP. Based on these findings, we propose a model whereby T4P unipolarity is accomplished by stimulation of T4P formation at the leading pole by MglA-GTP and SgmX and indirect inhibition of T4P formation at the lagging pole by MglB due to its MglA GAP activity. During reversals, MglA, SgmX, and MglB switch polarity, thus laying the foundation for T4P formation at the new leading pole and inhibition of T4P formation at the new lagging pole. |
Databáze: | OpenAIRE |
Externí odkaz: |
načítá se...