Identification of the Natural Transformation Genes in Riemerella anatipestifer by Random Transposon Mutagenesis

Li Huang; Mafeng Liu; Aparna Viswanathan Ammanath; Dekang Zhu; Renyong Jia; Shun Chen; Xinxin Zhao; Qiao Yang; Ying Wu; Shaqiu Zhang; Juan Huang; Xumin Ou; Sai Mao; Qun Gao; Di Sun; Bin Tian; Friedrich Götz; Mingshu Wang; Anchun Cheng

doi:10.3389/fmicb.2021.712198

Identification of the Natural Transformation Genes in Riemerella anatipestifer by Random Transposon Mutagenesis

Front Microbiol. 2021 Sep 9:12:712198. doi: 10.3389/fmicb.2021.712198. eCollection 2021.

Authors

Li Huang^{1

2

3}, Mafeng Liu^{1

2

3}, Aparna Viswanathan Ammanath⁴, Dekang Zhu^{2

3}, Renyong Jia^{1

2

3}, Shun Chen^{1

2

3}, Xinxin Zhao^{1

2

3}, Qiao Yang^{1

2

3}, Ying Wu^{1

2

3}, Shaqiu Zhang^{1

2

3}, Juan Huang^{1

2

3}, Xumin Ou^{1

2

3}, Sai Mao^{1

2

3}, Qun Gao^{1

2

3}, Di Sun^{1

2

3}, Bin Tian^{1

2

3}, Friedrich Götz⁴, Mingshu Wang^{1

2

3}, Anchun Cheng^{1

2

3}

Affiliations

¹ Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.
² Research Centre of Avian Disease, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.
³ Key Laboratory of Animal Disease and Human Health of Sichuan Province, Chengdu, China.
⁴ Microbial Genetics, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), University of Tübingen, Tübingen, Germany.

Abstract

In our previous study, it was shown that Riemerella anatipestifer, a Gram-negative bacterium, is naturally competent, but the genes involved in the process of natural transformation remain largely unknown. In this study, a random transposon mutant library was constructed using the R. anatipestifer ATCC11845 strain to screen for the genes involved in natural transformation. Among the 3000 insertion mutants, nine mutants had completely lost the ability of natural transformation, and 14 mutants showed a significant decrease in natural transformation frequency. We found that the genes RA0C_RS04920, RA0C_RS04915, RA0C_RS02645, RA0C_RS04895, RA0C_RS05130, RA0C_RS05105, RA0C_RS09020, and RA0C_RS04870 are essential for the occurrence of natural transformation in R. anatipestifer ATCC11845. In particular, RA0C_RS04895, RA0C_RS05130, RA0C_RS05105, and RA0C_RS04870 were putatively annotated as ComEC, DprA, ComF, and RecA proteins, respectively, in the NCBI database. However, RA0C_RS02645, RA0C_RS04920, RA0C_RS04915, and RA0C_RS09020 were annotated as proteins with unknown function, with no homology to any well-characterized natural transformation machinery proteins. The homologs of these proteins are mainly distributed in the members of Flavobacteriaceae. Taken together, our results suggest that R. anatipestifer encodes a unique natural transformation machinery.

Keywords: Flavobacteriaceae; Riemerella anatipestifer; horizontal gene transfer; natural transformation; random transposon mutagenesis.