AUTHOR=Yang Yimin , Lin Mi , Chen Xueqiu , Zhao XianFeng , Chen Lulu , Zhao Mingxiu , Yao Chaoqun , Sheng Kaiyin , Yang Yi , Ma Guangxu , Du Aifang 

TITLE=The first apicoplast tRNA thiouridylase plays a vital role in the growth of Toxoplasma gondii

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2022.947039

DOI=10.3389/fcimb.2022.947039

ISSN=2235-2988

ABSTRACT=<p>Toxoplasmosis caused by the protozoan <italic>Toxoplasma gondii</italic> is one of the most common parasitic diseases in humans and almost all warm-blooded animals. Lys, Glu, and Gln-specific tRNAs contain a super-modified 2-thiourea (s<sup>2</sup>U) derivatives at the position 34, which is essential for all living organisms by maintaining the structural stability and aminoacylation of tRNA, and the precision and efficiency of codon recognition during protein translation. However, the enzyme(s) involved in this modification in <italic>T. gondii</italic> remains elusive. In this report, three putative tRNA-specific 2-thiolation enzymes were identified, of which two were involved in the s<sup>2</sup>U34 modification of tRNA<sup>Lys</sup>, tRNA<sup>Glu</sup>, and tRNA<sup>Gln</sup>. One was named <italic>Tg</italic>MnmA, an apicoplast-located tRNA-specific 2-thiolation enzyme in <italic>T. gondii</italic>. Knockout of <italic>TgMnmA</italic> showed that this enzyme is important for the lytic cycle of tachyzoites. Loss of <italic>Tg</italic>MnmA also led to abnormities in apicoplast biogenesis and severely disturbed apicoplast genomic transcription. Notably, mice survived from the infection with 10 <italic>Tg</italic>MnmA-KO RH tachyzoites. These findings provide new insights into s<sup>2</sup>U34 tRNA modification in Apicomplexa, and suggest <italic>Tg</italic>MnmA, the first apicoplast tRNA thiouridylase identified in all apicomplexans, as a potential drug target.</p>