AUTHOR=Liang Jialei , Zhou Kexin , Li Qiaoling , Dong Xu , Zhang Peiyao , Liu Hongmao , Lin Hailong , Zhang Xueya , Lu Junwan , Lin Xi , Li Kewei , Xu Teng , Zhang Hailin , Bao Qiyu , Zhu Mei , Hu Yunliang , Ren Ping 

TITLE=Identification and Characterization of a Novel Aminoglycoside 3''-Nucleotidyltransferase, ANT(3'')-IId, From Acinetobacter lwoffii

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.728216

DOI=10.3389/fmicb.2021.728216

ISSN=1664-302X

ABSTRACT=<p>A novel plasmid-encoded aminoglycoside 3''-nucleotidyltransferase ANT(3")-IId, was discovered in <italic>Acinetobacter lwoffi</italic> strain H7 isolated from a chick on an animal farm in Wenzhou, China. The whole-genome of <italic>A. lwoffii</italic> H7 consisted of one chromosome and five plasmids (pH7-250, pH7-108, pH7-68, pH7-48, and pH7-11). <italic>ant(3")-IId</italic> was identified as being encoded on pH7-250, sharing the highest amino acid identity of 50.64% with a function-known resistance gene, <italic>ant(3")-IIb</italic> (KB849358.1). Susceptibility testing and enzyme kinetic parameter analysis were conducted to determine the function of the aminoglycoside 3"-nucleotidyltransferase. The <italic>ant(3")-IId</italic> gene conferred resistance to spectinomycin and streptomycin [the minimum inhibitory concentration (MIC) levels of both increased 16-fold compared with the control strain]. Consistent with the MIC data, kinetic analysis revealed a narrow substrate profile including spectinomycin and streptomycin, with <italic>K</italic><sub>cat</sub>/<italic>K</italic><sub>m</sub> ratios of 4.99 and 4.45×10<sup>3</sup>M<sup>−1</sup> S<sup>−1</sup>, respectively. Sequencing analysis revealed that the <italic>ant(3")-IId</italic> gene was associated with insertion sequences (IS) element [ΔIS<italic>Aba14</italic>-ΔIS<italic>Aba14</italic>-hp-orf-orf-orf1-<italic>ant(3")-IId</italic>], and <italic>ant(3")-IId</italic> were identified in plasmids from various <italic>Acinetobacter</italic> species. This study of the novel aminoglycoside 3"-nucleotidyltranferase ANT(3")-IId helps us further understand the functional and sequence characteristics of aminoglycoside 3"-nucleotidyltranferases, highlights the risk of resistance gene transfer among <italic>Acinetobacter</italic> species and suggests that attention should be given to the emergence of new aminoglycoside 3"-nucleotidyltranferase genes.</p>