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CryoEM structures of open dimers of gyrase A in complex with DNA illuminate mechanism of strand passage.

ABSTRACT: Gyrase is a unique type IIA topoisomerase that uses ATP hydrolysis to maintain the negatively supercoiled state of bacterial DNA. In order to perform its function, gyrase undergoes a sequence of conformational changes that consist of concerted gate openings, DNA cleavage, and DNA strand passage events. Structures where the transported DNA molecule (T-segment) is trapped by the A subunit have not been observed. Here we present the cryoEM structures of two oligomeric complexes of open gyrase A dimers and DNA. The protein subunits in these complexes were solved to 4 Å and 5.2 Å resolution. One of the complexes traps a linear DNA molecule, a putative T-segment, which interacts with the open gyrase A dimers in two states, representing steps either prior to or after passage through the DNA-gate. The structures locate the T-segment in important intermediate conformations of the catalytic cycle and provide insights into gyrase-DNA interactions and mechanism.

SUBMITTER: Soczek KM

PROVIDER: S-EPMC6286129 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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CryoEM structures of open dimers of gyrase A in complex with DNA illuminate mechanism of strand passage.

Soczek Katarzyna M KM Grant Tim T Rosenthal Peter B PB Mondragón Alfonso A

eLife 20181120

Gyrase is a unique type IIA topoisomerase that uses ATP hydrolysis to maintain the negatively supercoiled state of bacterial DNA. In order to perform its function, gyrase undergoes a sequence of conformational changes that consist of concerted gate openings, DNA cleavage, and DNA strand passage events. Structures where the transported DNA molecule (T-segment) is trapped by the A subunit have not been observed. Here we present the cryoEM structures of two oligomeric complexes of open gyrase A dim ...[more]

PMID: 30457554

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