Probing the ATP-binding site of P1 ParA: partition and repression have different requirements for ATP binding and hydrolysis

AUTOR(ES)

Fung, Emma

FONTE

Oxford University Press

RESUMO

The ParA family of proteins is involved in partition of a variety of plasmid and bacterial chromosomes. P1 ParA plays two roles in partition: it acts as a repressor of the par operon and has an undefined yet indispensable role in P1 plasmid localization. We constructed seven mutations in three putative ATP-binding motifs of ParA. Three classes of phenotypes resulted, each represented by mutations in more than one motif. Three mutations created ‘super-repressors’, in which repressor activity was much stronger than in wild-type ParA, while the remainder damaged repressor activity. All mutations eliminated partition activities, but two showed a plasmid stability defect that was worse than that of a null mutation. Four mutant ParAs, two super-repressors and two weak repressors, were analyzed biochemically, and all exhibited damaged ATPase activity. The super-repressors bound site-specifically to the par operator sequence, and this activity was strongly stimulated by ATP and ADP. These results support the proposal that ATP binding is essential but hydrolysis is inhibitory for ParA’s repressor activity and suggest that ATP hydrolysis is essential for plasmid localization.

Documentos Relacionados

• Identification of the ATP-binding site in the terminase subunit pUL56 of human cytomegalovirus
• Vanadate trapping of nucleotide at the ATP-binding sites of human multidrug resistance P-glycoprotein exposes different residues to the drug-binding site
• Partition site of the P1 plasmid.
• Mechanism of Coupling of Transport to Hydrolysis in Bacterial ATP-Binding Cassette Transporters
• par-2, a gene required for blastomere asymmetry in Caenorhabditis elegans, encodes zinc-finger and ATP-binding motifs.