Nonribosomal peptides （NRPs） represent a large family of natural products with great diversities of chemical structures and biological activities. The peptide backbones of NRPs are synthesized by nonribosomal peptide synthetases （NRPSs） that minimally consist of one adenylation （A） domain, one peptidyl carrier protein （PCP） and one condensation （C） domain. In this study, we carded out a PCR screening and identified 21 ＂positive＂ strains from 100 actinomycete strains with the degenerate primers designed from the conserved sequences of A domains of NRPSs. One of the 21 ＂positive＂ strains, Streptomyces sp. HMU0027, was selected for large-scale fermentation （9 L） based on HPLC analysis, and subsequent isolation and structural elucidation afforded seven NRPS-synthesized thiazostatin siderophore analogues （1-7）. Compound 1 was a new compound containing an unusual linkage between a phenolate siderophore and a sugar moiety. These results laid the foundation for further biosynthetic research of these thiazostatin analogues and highlighted the power of genome mining technologies based on biosynthetic knowledge in NRP discovery.
ING1(inhibitor of growth 1)是一个候选抑癌基因家族,p47ING1a、p33ING1b和p24ING1c是其三种剪接异构体.通过MTT法和流式细胞术研究ING1a、ING1b和ING1c对HeLa细胞增殖的影响,结果发现三者均可将HeLa细胞阻滞于G0/G1期并抑制细胞生长.采用PCR方法构建ING1a和ING1b的PHD结构域缺失体1a!C和1b!C,进而使ING1a,ING1b、ING1c、1a△C和1b△C在HeLa细胞中过表达.采用Western blot检测上述HeLa细胞中p16INK4a、PTEN/p27Kip1和p53/p21Waf1的表达变化,结果发现ING1a、ING1b、ING1c和1a△C均可促进p16INK4a的表达,其中ING1c的促进作用最为显著,1b△C则略微抑制了p16INK4a的蛋白质表达.利用荧光素酶分析初步确定1a△C可增强p16INK4a启动子活性而促进p16INK4a的转录,1b△C则抑制了p16INK4a启动子活性.上述结果阐释了ING1家族各成员对HeLa细胞增殖的影响及其分子机制,从而确定了各异构体功能的异同及它们所调控的重要基因.首次发现除p53/p21Waf1通路外,ING1家族各异构体还可通过上调p16INK4a和PTEN的表达而抑制肿瘤细胞生长,并且ING1a的PHD结构域删除体可以增强p16INK4a的转录,这为研究ING1家族抑制肿瘤细胞生长的分子机制提供了新的线索.
