INDUCIBLE ERYTHROMYCIN RESISTANCE

这项研究是在基因调控的一般领域， 红霉素特异性和有效地诱导 对自身和其他大环内酯类、林可酰胺类和 链阳性菌素B（MLS）抗生素。 诱导型23 S的合成 负责MLS抗性的核糖体RNA甲基化酶被控制在 通过构象调节的衰减剂的翻译水平 通过确定核糖体装载位点的可用性， 抗性甲基化酶的翻译起始。 的一个主要 在这项工作中没有回答的问题是：什么机制占 不同亚群的诱导效率的明显宽变异性 MLS抗生素在不同的细菌，尽管显然平等 这些抗生素作为抑制剂的有效性？ 的长期目标 这项计划是研究和测试基因表达调控的模型， 重点是指定抗生素耐药性的基因; 该建议的目的是研究诱导型MLS抗性的调节 模型系统通过：（2）确定体内诱导特异性， 将化学合成的模型前导序列插入表达 为这项工作构建的载体，（2）确定氨基酸序列，或 涉及前导肽的突变体中的密码子使用改变， 可能相关的诱导特异性改变，和（3）研究 诱导特异性和衰减剂功能。 这些归纳的研究为理解快速归纳提供了一个模型。 在短时间内发展组成性MLS抗性， 在临床环境中使用MLS抗生素治疗。 诱导型MLS 在产生MLS抗生素的链霉菌中也发现了耐药性， 在某些情况下，在细胞进入之前， 抗生素生产。 我们的工作假设是，在自然界中， 肽用于优化抗生素生产和 产生抵抗力，或者更一般地说， 和特定基因的表达增加。 中使用的方法 这些研究包括应用重组DNA技术和DNA测序 涉及克隆通过化学方法合成的模型DNA衰减子序列， 分析来自自然资源的新控制序列。

The research proposed is in the general area of gene regulation studied in a model system in which erythromycin specifically and efficiently induces resistance to itself and other macrolides, to the lincosamides, and to the streptogramin B (MLS) antibiotics. Synthesis of the inducible 23S ribosomal RNA methylase responsible for MLS resistance is controlled at the translational level by an attenuator whose conformation regulates expression by determining availability of the ribosome loading site for translation initiation of the resistance methylase. One of the main unanswered questions in this work is: What mechanism accounts for the apparent wide variability of induction efficiency of different subsets of MLS antibiotics in different bacteria despite the apparently equal efficiency of these antibiotics as inhibitors? The long term objective of this proposal is to study and test models of regulation of gene expression with emphasis on genes that specify antibiotic resistance; The specific aims of this proposal are to study regulation of inducible MLS resistance model systems by: (2) determining induction specificity in vivo following insertion of chemically synthesized model leader sequences into expression vectors constructed for this work, (2) determining amino acid sequence or codon usage alterations in mutants that involve the leader peptide and show possible associated altered specificity of induction, and (3) studying induction specificity and attenuator function in new bacterial strains. These studies of induction provide a model for understanding rapid development of constitutive MLS resistance following a short course of treatment with MLS antibiotics in a clinical setting. Inducible MLS resistance is also found in Streptomyces that produce MLS antibiotics and in some instances resistance is not expressed before the cells enter antibiotic production. It is our working hypothesis that in nature, leader peptides serve to optimize the coupling between antibiotic production and development of resistance, or more generally, between inductive stimulus and increased expression of specific genes. Methods that will be used in these studies include recombinant DNA technology and DNA sequencing applied to cloning model DNA attenuator sequences synthesized by chemical means and analyzing new control sequences from natural resources.