Open AccessMembrane Sequestration of PII Proteins and Nitrogenase Regulation in the Photosynthetic Bacterium Rhodobacter capsulatus
Author(s) -
Pier-Luc Tremblay,
Thomas Drepper,
Bernd Masepohl,
Patrick C. Hallenbeck
Publication year - 2007
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.00680-07
Subject(s) - rhodobacter , biology , biochemistry , nitrogenase , mutant , ammonium , rhodospirillales , bacteria , membrane protein , membrane , photosynthesis , nitrogen fixation , chemistry , gene , genetics , organic chemistry
BothRhodobacter capsulatus PII homologs GlnB and GlnK were found to be necessary for the proper regulation of nitrogenase activity and modification in response to an ammonium shock. As previously reported for several other bacteria, ammonium addition triggered the AmtB-dependent association of GlnK with theR. capsulatus membrane. Native polyacrylamide gel electrophoresis analysis indicates that the modification/demodification of one PII homolog is aberrant in the absence of the other. In aglnK mutant, more GlnB was found to be membrane associated under these conditions. In aglnB mutant, GlnK fails to be significantly sequestered by AmtB, even though it appears to be fully deuridylylated. Additionally, the ammonium-induced enhanced sequestration by AmtB of the unmodifiable GlnK variant GlnK-Y51F follows the wild-type GlnK pattern with a high level in the cytoplasm without the addition of ammonium and an increased level in the membrane fraction after ammonium treatment. These results suggest that factors other than PII modification are driving its association with AmtB in the membrane inR. capsulatus .