PT  - JOURNAL ARTICLE
AU  - Annika Breidenstein
AU  - Josy ter Beek
AU  - Ronnie P-A Berntsson
TI  - Structural and functional characterization of TraI from pKM101 reveals basis for DNA processing
AID  - 10.1101/2022.06.02.494495
DP  - 2022 Jan 01
TA  - bioRxiv
PG  - 2022.06.02.494495
4099  - http://biorxiv.org/content/early/2022/06/02/2022.06.02.494495.short
4100  - http://biorxiv.org/content/early/2022/06/02/2022.06.02.494495.full
AB  - To support conjugation via Type 4 Secretion Systems, relaxases perform the initial processing of the substrate DNA. TraI from the well-studied conjugative plasmid pKM101 is one such relaxase, which has not yet been characterized. Here, we report the crystal structure of the trans-esterase domain of TraI in complex with its substrate oriT DNA, highlighting the conserved DNA binding mechanism. Additionally, we present an apo structure of the trans-esterase domain of TraI, which allows us to visualize the conformational changes involved in DNA binding. We also show a complete characterization of the DNA binding, nicking and religation of the trans-esterase domain, helicase domain and full-length TraI. Furthermore, TraI is shown to be a tetramer. These results reveal that the trans-esterase domain behaves in a similar way as its homologs TraI from the F plasmid and TrwC from R388, but the tetramerization of the full-length protein highlights a significant difference that affects the function of TraI.Competing Interest StatementThe authors have declared no competing interest.