Bacterial genome partitioning: N-terminal domain of IncC protein encoded by broad-host-range plasmid RK2 modulates oligomerisation and DNA binding.
ParA Walker ATPases form part of the machinery that promotes better-than-random segregation of bacterial genomes. ParA proteins normally occur in one of two forms, differing by their N-terminal domain (NTD) of approximately 100 aa, which is generally associated with site-specific DNA binding. Unusually, and for as yet unknown reasons, parA (incC) of IncP-1 plasmids is translated from alternative start codons producing two forms, IncC1 (364 aa) and IncC2 (259 aa), whose ratio varies between hosts. IncC2 could be detected as an oligomeric form containing dimers, tetramers and octamers, but the N-terminal extension present in IncC1 favours nucleotide-stimulated dimerisation as well as high-affinity and ATP-dependent non-specific DNA binding. The IncC1 NTD does not dimerise or bind DNA alone, but it does bind IncC2 in the presence of nucleotides. Mixing IncC1 and IncC2 improved polymerisation and DNA binding. Thus, the NTD may modulate the polymerisation interface, facilitating polymerisation/depolymerisation and DNA binding, to promote the cycle that drives partitioning.
Batt
Sarah M
SM
School of Biosciences, University of Birmingham, Edgbaston, Birmingham, UK.
Bingle
Lewis E H
LE
Dafforn
Tim R
TR
Thomas
Christopher M
CM
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D018387:Codon, Initiator; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D010957:Plasmids; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary
D018387:Codon, Initiator; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D020033:Protein Isoforms; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate