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Self-organization of parS centromeres by the ParB CTP hydrolase

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Science  29 Nov 2019:
Vol. 366, Issue 6469, pp. 1129-1133
DOI: 10.1126/science.aay3965

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CTP hydrolysis organizes chromosomes

The bacterial DNA parS centromere recruits the ParB protein to the bacterial chromosome. Soh et al. found that the widespread family of ParB proteins not only bind DNA but also bind and hydrolyze cytidine triphosphate (CTP) (see the Perspective by Funnell). ParB CTP hydrolysis is stimulated by parS and regulates the spreading of ParB protein to the parS flanking regions, which is crucial for organizing the bacterial chromosome. The cytidine triphosphatase domain is conserved in a large variety of protein sequences, suggesting its potential roles in other cellular processes.

Science, this issue p. 1129; see also p. 1072

Abstract

ParABS systems facilitate chromosome segregation and plasmid partitioning in bacteria and archaea. ParB protein binds centromeric parS DNA sequences and spreads to flanking DNA. We show that ParB is an enzyme that hydrolyzes cytidine triphosphate (CTP) to cytidine diphosphate (CDP). parS DNA stimulates cooperative CTP binding by ParB and CTP hydrolysis. A nucleotide cocrystal structure elucidates the catalytic center of the dimerization-dependent ParB CTPase. Single-molecule imaging and biochemical assays recapitulate features of ParB spreading from parS in the presence but not absence of CTP. These findings suggest that centromeres assemble by self-loading of ParB DNA sliding clamps at parS. ParB CTPase is not related to known nucleotide hydrolases and might be a promising target for developing new classes of antibiotics.

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