Albrecht Mario, Lengauer Thomas
Max-Planck-Institute for Informatics, Stuhlsatzenhausweg 85, 66123 Saarbrücken, Germany.
FEBS Lett. 2004 Jul 2;569(1-3):18-26. doi: 10.1016/j.febslet.2004.03.126.
Sm and Sm-like proteins of the Lsm (like Sm) domain family are generally involved in essential RNA-processing tasks. While recent research has focused on the function and structure of small family members, little is known about Lsm domain proteins carrying additional domains. Using an integrative bioinformatics approach, we discovered five novel groups of Lsm domain proteins (Lsm12-16) with long C-terminal tails and investigated their functions. All of them are evolutionarily conserved in eukaryotes with an N-terminal Lsm domain to bind nucleic acids followed by as yet uncharacterized C-terminal domains and sequence motifs. Based on known yeast interaction partners, Lsm12-16 may play important roles in RNA metabolism. Particularly, Lsm12 is possibly involved in mRNA degradation or tRNA splicing, and Lsm13-16 in the regulation of the mitotic G2/M phase. Lsm16 proteins have an additional C-terminal YjeF_N domain of as yet unknown function. The identification of an additional methyltransferase domain at the C-terminus of one of the Lsm12 proteins also led to the recognition of three new groups of methyltransferases, presumably dependent on S-adenosyl-l-methionine. Further computational analyses revealed that some methyltransferases contain putative RNA-binding helix-turn-helix domains and zinc fingers.
Lsm（类Sm）结构域家族的Sm和类Sm蛋白通常参与重要的RNA加工任务。虽然最近的研究集中在小家族成员的功能和结构上，但对于携带额外结构域的Lsm结构域蛋白却知之甚少。我们采用综合生物信息学方法，发现了五组具有长C末端尾巴的新型Lsm结构域蛋白（Lsm12 - 16），并对其功能进行了研究。它们在真核生物中均具有进化保守性，其N末端有一个Lsm结构域用于结合核酸，随后是尚未明确特征的C末端结构域和序列基序。基于已知的酵母相互作用伙伴，Lsm12 - 16可能在RNA代谢中发挥重要作用。特别是，Lsm12可能参与mRNA降解或tRNA剪接，而Lsm13 - 16参与有丝分裂G2/M期的调控。Lsm16蛋白在C末端还有一个功能未知的YjeF_N结构域。在其中一个Lsm12蛋白的C末端鉴定出一个额外的甲基转移酶结构域，这也导致识别出三组新的甲基转移酶，推测它们依赖于S - 腺苷 - L - 甲硫氨酸。进一步的计算分析表明，一些甲基转移酶含有假定的RNA结合螺旋 - 转角 - 螺旋结构域和锌指结构。
