FdTonB is involved in the photoregulation of cellular morphology during complementary chromatic adaptation in Fremyella diplosiphon.
We have characterized a Fremyella diplosiphon TonB protein (FdTonB) and investigated its function during complementary chromatic adaptation. Sequence similarity analysis of FdTonB (571 aa) led to identification of several conserved domains characteristic of TonB proteins, including an N-terminal transmembrane domain, a central proline-rich spacer and a C-terminal TonB-related domain (TBRD). We identified a novel glycine-rich domain containing (Gly-X)(n) repeats. To assess FdTonB function, we constructed a DeltatonB mutant through homologous recombination based upon truncation of the central proline-rich spacer, glycine-rich domain and TBRD. Our DeltatonB mutant exhibited an aberrant cellular morphology under green light, with expanded cell width compared to the parental wild-type (WT) strain. The cellular morphology of the DeltatonB mutant recovered upon WT tonB expression. Interestingly, tonB expression was found to be independent of RcaE. As DeltatonB and WT strains respond in the same way when grown under iron-replete versus iron-limited conditions, our results suggest that FdTonB is not involved in the classic TonB function of mediating cellular adaptation to iron limitation, but exhibits a novel function related to the photoregulation of cellular morphology in F. diplosiphon.
Pattanaik
Bagmi
B
Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA.
Montgomery
Beronda L
BL
Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.|Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA.
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D019295:Computational Biology; D000458:Cyanobacteria / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism / Q000528:radiation effects; D015964:Gene Expression Regulation, Bacterial; D007501:Iron / Q000378:metabolism; D008027:Light; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009154:Mutation; D010858:Pigmentation; D012329:RNA, Bacterial / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D008565:Membrane Proteins; D012329:RNA, Bacterial; C057616:tonB protein, Bacteria; D007501:Iron