DprA Is Essential for Natural Competence in Riemerella anatipestifer and Has a Conserved Evolutionary Mechanism

Abstract

Riemerella anatipestifer ATCC11845 (RA ATCC11845) is naturally competent. However, the genes involved in natural transformation in this species remain largely unknown. Bioinformatic analysis predicts that DprA of RA (DprA Ra ) has three domains: a sterile alpha motif (SAM), a Rossmann fold (RF) domain and a Z-DNA-binding domain (Zα). Inactivation of dprA abrogated natural transformation in RA ATCC11845, and this effect was restored by the expression of dprA in trans . The dprA with SAM and RF domains of Streptococcus pneumoniae and the dprA with RF and Zα domains of Helicobacter pylori was able to restore natural transformation in the RA ATCC11845 dprA mutant. An Arg123 mutation in the RF domain of R. anatipestifer was not able to restore natural transformation of the RA ATCC11845 dprA mutant. Furthermore, DprA R123E abolished its ability to bind DNA, suggesting that the RF domain is essential for the function of DprA. Finally, the dprA of Fusobacterium naviforme which has not been reported to be natural competent currently was partially able to restore natural transformation in RA ATCC11845 dprA mutant. These results collectively suggest that DprA has a conserved evolutionary mechanism.

Functional characterization of Fur in iron metabolism, oxidative stress resistance and virulence of Riemerella anatipestifer

“…DNA mobility shift assays were performed using the method described in a previous study, with minor modifications [ 38 ]. The promoter regions of the B739_0173 and B739_0173 -coding regions (204 bp and 214 bp, respectively) were amplified by PCR with the primers B739_0173 promoter P1/P2 and B739_0173 coding region P1/P2 (Additional file 2 ).…”

Natural Transformation of Riemerella columbina and Its Determinants

“…The bacterial strains and primers used in this study are listed in Table 1 . The culture conditions for R. columbina and F. johnsoniae were identical to those used for R. anatipestifer described in a previous study ( Huang et al, 2019 ). Briefly, R. columbina was cultured in GC broth (GCB) medium with shaking or GCB agar plates and LB plates supplemented with 5% sheep blood (blood plates) at 37°C, however, F. johnsoniae was cultured in GCB medium with shaking or GCB plates at 25°C.…”

“…Once dsDNA is transported across the outer membrane in Gram-negative bacteria or the peptidoglycan layer in Gram-positive bacteria, dsDNA is degraded to single-stranded DNA (ssDNA) and transported through the pore protein ComEC into the cytoplasm ( Johnston et al, 2014 ). Internalized ssDNA is presumably bound by DNA-processing protein A (DprA), which recruits the recombinase RecA to mediate homologous recombination by facilitating strand exchange ( Johnston et al, 2014 ; Huang et al, 2019 ). At present, the natural transformation of H. influenzae in Pasteurellaceae , Vibrio cholerae in Vibrionaceae , and S. pneumoniae in Streptococcaceae are well studied ( Redfield et al, 2006 ; Blokesch, 2012 ; Johnston et al, 2014 ).…”

The Clustered Regularly Interspaced Short Palindromic Repeat System and Argonaute: An Emerging Bacterial Immunity System for Defense Against Natural Transformation?

“…ComM subsequently promotes expansion of the D-loop using a bidirectional helicase and branch migration activities that enhance the integration efficiency of ssDNA into the genome (Nero et al, 2018; Figure 1C). The biological functions and mechanisms of action for ComE(A), ComEC, DprA, RecA, and ComM are all evolutionarily conserved in most competent bacteria (Provvedi and Dubnau, 1999;Berge et al, 2002;Draskovic and Dubnau, 2005;Berge et al, 2013;Johnston et al, 2013;Johnston et al, 2014;Seitz et al, 2014;Hepp and Maier, 2016;Salzer et al, 2016;Nero et al, 2018;Pimentel and Zhang, 2018;Huang et al, 2019).…”