POST-TRANSCRIPTIONAL RRNA MODIFICATION FOR THE 30S RIBOSOMAL SUBUNIT

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 核糖体RNA和蛋白质的转录后和翻译后修饰在大多数生物体中是常见的，但其中许多修饰的功能尚不清楚。在细菌中，一些修饰的丧失导致对抗生素药物的抗性增加或减少。我们研究了这些修饰对核糖体结构和功能的意义。该项目是与布朗大学的Albert Dahlberg，英国MRC的Venki Ramakrishnan和APS的Frank Murphy合作进行的。我们现在已经从T.缺失rRNA甲基转移酶KsgA基因的嗜热菌。KsgA二甲基转移酶修饰16 S rRNA的残基A1518和A1519。这种修饰似乎在所有生物体中是保守的，并赋予对抗生素春日霉素的敏感性。未修饰的30 S亚基的结构信息将导致更好地理解这些修饰的功能。 在第二种方法中，我们正在研究突变对核糖体结构的影响。我们已经产生了两种突变形式的30 S亚基晶体：链霉素依赖性突变体G524 U和回复突变体G524 U/A10 G。我们计划确定突变体30 S核糖体亚基在apo形式和与链霉素复合的结构，以了解导致突变形式中抗生素结合改变的重排。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Post-transcriptional and post-translational modification of ribosomal RNA and proteins is common in most or-ganisms, but the function of many of these modifications is not known. In bacteria, loss of some modifications leads to increased or decreased resistance to antibiotic drugs. We investigate the significance of these modi-fications for ribosome structure and function. This project is carried out in collaboration with Albert Dahlberg at Brown University, Venki Ramakrishnan at the MRC, UK, and Frank Murphy at the APS. We have now produced crystals for 30S ribosomal subunits from T. thermophilus with the gene for the rRNA methyltrans-ferase KsgA deleted. The KsgA dimethyltransferase modifies residues A1518 and A1519 of the 16S rRNA. This modification appears to be conserved in all organisms and confers sensitivity to the antibiotic kasu-gamycin. Structural information for the unmodified 30S subunits will lead to a better understanding of the function of these modifications. In a second approach, we are studying the impact of mutations on ribosome structure. We have produced 30S subunit crystals for two mutant forms: the streptomycin-dependent mutant G524U and the reverting double mutant G524U / A10G. We plan to determine structures of the mutant 30S ribosomal subunits in the apo-form and in complex with streptomycin to understand the rearrangements that lead to the altered binding of the antibiotic in the mutant forms.