Dmochowska A, Konopińska A, Krzymowska M, Szcześniak B, Boguta M
Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw.
Gene. 1995 Aug 30;162(1):81-5. doi: 10.1016/0378-1119(95)00311-s.
The nuclear gene NAM9 from Saccharomyces cerevisiae (Sc) codes for a protein which, on the basis of sequence homology, was previously postulated to be a mitochondrial (mt) equivalent of the Escherichia coli (Ec) S4 ribosomal protein (r-protein) [Boguta et al., Mol. Cell. Biol. 12 (1992) 402-412]. The mt-r character of the NAM9 product is now confirmed by cross-reaction with the antisera for the Sc mt r-proteins. The NAM9-1 mutation, characterized previously as the nuclear suppressor of some ochre mt mit- mutants, is found to be a single nucleotide substitution changing Ser82 to Leu within the part of NAM9 corresponding to the S4 region involved in interaction with the 16S rRNA. This indicates that the mechanism of NAM9-1 suppression could be analogous to the suppression due to ram (ribosomal ambiguity) mutations in the Ec structural gene encoding r-protein S4. The NAM9-1 mutation leads also to defect in respiratory growth in the background of the wild-type mit+ genome.
酿酒酵母（Sc）的核基因NAM9编码一种蛋白质，基于序列同源性，先前推测该蛋白质是大肠杆菌（Ec）S4核糖体蛋白（r蛋白）的线粒体（mt）等同物[博古塔等人，《分子与细胞生物学》12（1992年）402 - 412]。现在通过与Sc线粒体r蛋白抗血清的交叉反应证实了NAM9产物的线粒体r蛋白特性。先前被表征为一些赭石型线粒体mit - 突变体的核抑制因子的NAM9 - 1突变，被发现是一个单核苷酸替换，在NAM9对应于与16S rRNA相互作用的S4区域的部分内，将Ser82变为Leu。这表明NAM9 - 1抑制机制可能类似于Ec编码r蛋白S4的结构基因中由于ram（核糖体模糊性）突变导致的抑制。NAM9 - 1突变在野生型mit + 基因组背景下也导致呼吸生长缺陷。
