Identification and characterization of two uvrA genes of Xanthomonas axonopodis pathovar citri

Abstract

Two uvrA-like genes, designated uvrA1 and uvrA2, that may be involved in nucleotide excision repair in Xanthomonas axonopodis pv. citri (X. a. pv. citri) strain XW47 were characterized. The uvrA1 gene was found to be 2,964 bp in length capable of encoding a protein of 987 amino acids. The uvrA2 gene was determined to be 2,529 bp with a coding potential of 842 amino acids. These two proteins share 71 and 39% identity, respectively, in amino acid sequence with the UvrA protein of Escherichia coli. Analyses of the deduced amino acid sequence revealed that UvrA1 and UvrA2 have structures characteristic of UvrA proteins, including the Walker A and Walker B motifs, zinc finger DNA binding domains, and helix-turn-helix motif with a polyglycine hinge region. The uvrA1 or uvrA2 mutant, constructed by gene replacement, was more sensitive to DNA-damaging agents methylmethane sulfonate (MMS), mitomycin C (MMC), or ultraviolet (UV) than the wild type. The uvrA1 mutant was four orders of magnitude more sensitive to UV irradiation and two orders of magnitude more sensitive to MMS than the uvrA2 mutant. The uvrA1uvrA2 double mutant was one order of magnitude more sensitive to MMS, MMC, or UV than the uvrA1 single mutant. These results suggest that UvrA1 plays a more important role than UvrA2 in DNA repair in X. a. pv. citri. Both uvrA1 and uvrA2 genes were found to be constitutively expressed in the wild type and lexA1 or lexA2 mutant of X. a. pv. citri, and treatment of these cells with sublethal dose of MMC did not alter the expression of these two genes. Results of electrophoresis mobility shift assays revealed that LexA1 or LexA2 does not bind to either the uvrA1 or the uvrA2 promoter. These results suggest that uvrA expression in X. a. pv. citri is not regulated by the SOS response system.

Mechanistic insights into host adaptation, virulence and epidemiology of the phytopathogenXanthomonas

“…Deletion of pigC and pigG in X. campestris resulted in enhanced susceptibility to radiation from natural light but not to UV (Poplawsky et al 2000). Several UV sensitive mutants were identified in different Xanthomonas strains; most are related to response to oxidative stress and DNA repair (Martínez et al 1997;Shen et al 2007;Tondo et al 2016).…”

Mechanisms of stationary-phase mutagenesis in bacteria: mutational processes in pseudomonads

“…It has been suggested that UvrA2 proteins are rather involved in resistance to DNA intercalating drugs than in DNA repair (Goosen & Moolenaar, 2008). However, despite the lack of a UvrB‐binding domain, there is evidence that UvrA2 proteins can confer tolerance to DNA damage (Tanaka et al ., 2005; Shen et al ., 2007; Tark et al ., 2008). Recent studies by Timmins et al .…”

“…It has been suggested that UvrA2 proteins are rather involved in resistance to DNA intercalating drugs than in DNA repair . However, despite the lack of a UvrB-binding domain, there is evidence that UvrA2 proteins can confer tolerance to DNA damage (Tanaka et al, 2005;Shen et al, 2007;Tark et al, 2008). Recent studies by Timmins et al (2009) have revealed that UvrA2 from Deinococcus radiodurans interacts with UvrB, although the interaction is weak and transient.…”

A Decade of Biochemical and Structural Studies of the DNA Repair Machinery of Deinococcus radiodurans: Major Findings, Functional and Mechanistic Insight and Challenges

“…Class II UvrAs, also known as UvrA2, are found in many bacteria living in harsh environments and show a high degree of sequence similarity to UvrA1, but are missing the UvrB interaction domain. The precise role of UvrA2 remains unclear, but there is evidence that UvrA2s play a role in DNA repair and tolerance to DNA damaging agents, such as UV or chemical treatment [60], [61], [62]. The crystal structure of the ADP-bound dimeric drUvrA2 was solved to 2.3 Å resolution (Table 1 and Fig.…”