Characterization of 3'-Phosphate RNA Ligase Paralogs RtcB1, RtcB2, and RtcB3 from Myxococcus xanthus Highlights DNA and RNA 5'-Phosphate Capping Activity of RtcB3.

摘要: ABSTRACT Escherichia coli RtcB exemplifies a family of GTP-dependent RNA repair/splicing enzymes that join 3′-PO4 ends to 5′-OH via stable RtcB-(histidinyl-N)-GMP and transient RNA3′pp5′G intermediates. E. also transfers GMP DNA end form “capped” product, DNA3′pp5′G. homologs are found in multitude bacterial proteomes, many bacteria have genes encoding two or more paralogs; an extreme example is Myxococcus xanthus, which has six RtcBs. In this study, we purified, characterized, compared the biochemical activities three M. xanthus paralogs. We RtcB1 resembles its ability perform intra- intermolecular sealing HORNAp substrate capping end. RtcB2 can splice but 5-fold-lower ligase specific activity than RtcB1. contrast, RtcB3 distinctively feeble at ligating substrate, although it readily caps The novelty capacity cap 5′-PO4 GppDNA GppRNA products, respectively. As such, joins growing list (including 3′-phosphate cyclase RtcA thermophilic ATP-dependent ligases) either polynucleotide substrate. formed by be decapped pDNA repair enzyme aprataxin. IMPORTANCE comprise widely distributed ligases distinguished their formation 3′-GMP-capped RNAppG and/or DNAppG polynucleotides. mechanism repertoire well studied, unclear whether properties apply multiple A comparison paralogs, RtcB1, RtcB2, RtcB3, shows not all RtcBs created equal. standout findings concern (i) inactive as adept (ii) able GppRNA, reactions novel nucleic acid modifications.