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An essential GTP‐binding protein functions as a regulator for differentiation in Streptomyces coelicolor
Author(s) -
Okamoto Susumu,
Ochi Kozo
Publication year - 1998
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1998.01042.x
Subject(s) - streptomyces coelicolor , biology , gtp' , mycelium , gtp binding protein regulators , gene , microbiology and biotechnology , mutant , g protein , biochemistry , signal transduction , botany , enzyme
The Streptomyces coelicolor obg gene, which encodes a putative GTP‐binding protein of the Obg/Gtp1 family, was characterized. The obg gene was essential for viability. Introduction of multiple copies of obg into wild‐type S. coelicolor suppressed aerial mycelium formation. A single amino acid substitution at any of six positions was introduced into the GTP binding site of Obg, and the mutated proteins were expressed in wild‐type cells. Obg P168 → V exerted a more accentuated suppressive effect on aerial mycelium formation than did the wild‐type Obg protein. In contrast, Obg G171 → A accelerated the development of aerial mycelium. These results show that Obg protein functions as a pivotal regulator for the onset of cell differentiation through its ability to bind GTP. Western analysis revealed that expression of obg is regulated in a growth phase‐dependent manner, indicating a sharp decrease just after onset of aerial mycelium development or at the end of vegetative growth. Obg was a membrane‐bound protein as determined by immunoelectron microscopy.