title: Leucine-specific domain modulates the aminoacylation and proofreading functional cycle of bacterial leucyl-tRNA synthetase.
abstract: The leucine-specific domain (LSD) is a compact well-ordered module that participates in positioning of the conserved KMSKS catalytic loop in most leucyl-tRNA synthetases (LeuRSs). However, the LeuRS from Mycoplasma mobile (MmLeuRS) has a tetrapeptide GKDG instead of the LSD. Here, we show that the tetrapeptide GKDG can confer tRNA charging and post-transfer editing activity when transplanted into an inactive Escherichia coli LeuRS (EcLeuRS) that has had its LSD deleted. Reciprocally, the LSD, together with the CP1-editing domain of EcLeuRS, can cooperate when inserted into the scaffold of the minimal MmLeuRS, and this generates an enzyme nearly as active as EcLeuRS. Further, we show that LSD participates in tRNA(Leu) recognition and favours the binding of tRNAs harbouring a large loop in the variable arm. Additional analysis established that the Lys598 in the LSD is the critical residue for tRNA binding. Conversion of Lys598 to Ala simultaneously reduces the tRNA-binding strength and aminoacylation and editing capacities, indicating that these factors are subtly connected and controlled at the level of the LSD. The present work provides a novel framework of co-evolution between LeuRS and its cognate tRNA through LSD.
authors.affiliation: State Key Laboratory of Molecular Biology, Center for RNA Research, Institute of Biochemistry and Cell Biology, the Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Yan
authors.forename: Min
authors.initials: M
authors.lastname: Tan
authors.forename: Gilbert
authors.initials: G
authors.lastname: Eriani
authors.forename: En-Duo
authors.initials: ED
authors.lastname: Wang
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D007935:Leucine-tRNA Ligase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008239:Lysine / Q000737:chemistry; D009154:Mutation; D009174:Mycoplasma / Q000201:enzymology; D017434:Protein Structure, Tertiary; D017393:RNA Editing; D012356:RNA, Transfer, Leu / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity; D046249:Transfer RNA Aminoacylation
chemical_list: D001426:Bacterial Proteins; D012356:RNA, Transfer, Leu; D007935:Leucine-tRNA Ligase; D008239:Lysine