6ppj

Cryo-EM structure of AdnA(D934A)-AdnB(D1014A) in complex with AMPPNPCryo-EM structure of AdnA(D934A)-AdnB(D1014A) in complex with AMPPNP

6ppj, resolution 3.50Å Show:Asymmetric Unit Biological Assembly Structural highlights 6ppj is a 2 chain structure with sequence from "bacillus_smegmatis"_trevisan_1889 "bacillus smegmatis" trevisan 1889. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: Gene: pcrA_2, ERS451418_01974 ("Bacillus smegmatis" Trevisan 1889), pcrA_1, ERS451418_01973 ("Bacillus smegmatis" Trevisan 1889) Activity: DNA helicase, with EC number 3.6.4.12 Experimental data: Check Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Mycobacterial AdnAB is a heterodimeric helicase-nuclease that initiates homologous recombination by resecting DNA double-strand breaks (DSBs). The AdnA and AdnB subunits are each composed of an N-terminal motor domain and a C-terminal nuclease domain. Here we report cryoelectron microscopy (cryo-EM) structures of AdnAB in three functional states: in the absence of DNA and in complex with forked duplex DNAs before and after cleavage of the 5' single-strand DNA (ssDNA) tail by the AdnA nuclease. The structures reveal the path of the 5' ssDNA through the AdnA nuclease domain and the mechanism of 5' strand cleavage; the path of the 3' tracking strand through the AdnB motor and the DNA contacts that couple ATP hydrolysis to mechanical work; the position of the AdnA iron-sulfur cluster subdomain at the Y junction and its likely role in maintaining the split trajectories of the unwound 5' and 3' strands. Single-molecule DNA curtain analysis of DSB resection reveals that AdnAB is highly processive but prone to spontaneous pausing at random sites on duplex DNA. A striking property of AdnAB is that the velocity of DSB resection slows after the enzyme experiences a spontaneous pause. Our results highlight shared as well as distinctive properties of AdnAB vis-a-vis the RecBCD and AddAB clades of bacterial DSB-resecting motor nucleases. Structures and single-molecule analysis of bacterial motor nuclease AdnAB illuminate the mechanism of DNA double-strand break resection.,Jia N, Unciuleac MC, Xue C, Greene EC, Patel DJ, Shuman S Proc Natl Acad Sci U S A. 2019 Nov 18. pii: 1913546116. doi:, 10.1073/pnas.1913546116. PMID:31740608 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.