Abstract
DNA phosphorothioate (PT) modification, with sulfur replacing a nonbridging phosphate oxygen in a sequence and stereo specific manner, is a novel physiological variation in bacteria. But what effects on DNA properties PT modification has is still unclear. To address this, we prepared three double-stranded (ds) DNA decamers, d(CGPXGCCGCCGA) with its complementary strand d(TCGGCGPXGCCG) (where X = O or S, i.e., PT-free dsDNA, [Sp, Sp]-PT dsDNA or [Rp, Rp]-PT dsDNA) located in gene of Streptomyces lividans. Their melting temperature (Tm) measurement indicates that [Rp, Rp]-PT dsDNA is most unstable. Their electron transfer potential detection presents an order of anti-oxidation properties: Sp-PT DNA > Rp-PT DNA > PT-free DNA. Their NMR structures demonstrate that PT modification doesn’t change their B-form conformation. The sulfur in [Rp, Rp]-PT dsDNA locates in the major groove, with steric effects on protons in the sugar close to modification sites, resulting in its unstability, and facilitating its selectively interactions with ScoMcrA. We thought that PT modification was dialectical to the bacteria. It protects the hosting bacteria by working as antioxidant against H2O2, and acts as a marker, directing restriction enzyme observed in other hosts, like ScoMcrA, to correctly cleave the PT modified DNA, so that bacteria cannot spread and survive.
Highlights
DNA phosphorothioate (PT) modification is a novel physiological variation in a specific sequence and stereo (i.e., Rp-PT) manner (Fig. 1A–C), in which sulfur is incorporated into DNA backbone[1]
The DNA PT modification results in DNA degradation (Dnd) phenotype[3]
PT modified DNA isolation and P-S bond stereochemistry characterization were described in supplemental material and methods
Summary
The possible biological functions of PT dsDNA. Previously, the phosphorothioate DNA was suggested to act as antioxidant in diverse bacteria[14]. The [Rp, Rp]-PT DNA protects the hosting bacteria by working as antioxidant when the bacteria live with oxidants such as H2O2, on the other hand, [Rp, Rp]-PT DNA acts as a marker, directing restriction enzyme observed in other hosts, like ScoMcrA, to bind it and to correctly cleave the PT modified DNA, so that bacteria cannot spread and survive. This explains why PT modification is maintained in diverse bacteria
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
