Griffith Jacqulyn L, Coleman Laura E, Raymond Adam S, Goodson Summer G, Pittard William S, Tsui Circe, Devine Scott E
Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
Genetics. 2003 Jul;164(3):867-79. doi: 10.1093/genetics/164.3.867.
Retroviruses and their relatives, the long terminal repeat (LTR) retrotransposons, carry out complex life cycles within the cells of their hosts. We have exploited a collection of gene deletion mutants developed by the Saccharomyces Genome Deletion Project to perform a functional genomics screen for host factors that influence the retrovirus-like Ty1 element in yeast. A total of 101 genes that presumably influence many different aspects of the Ty1 retrotransposition cycle were identified from our analysis of 4483 homozygous diploid deletion strains. Of the 101 identified mutants, 46 had significantly altered levels of Ty1 cDNA, whereas the remaining 55 mutants had normal levels of Ty1 cDNA. Thus, approximately half of the mutants apparently affected the early stages of retrotransposition leading up to the assembly of virus-like particles and cDNA replication, whereas the remaining half affected steps that occur after cDNA replication. Although most of the mutants retained the ability to target Ty1 integration to tRNA genes, 2 mutants had reduced levels of tRNA gene targeting. Over 25% of the gene products identified in this study were conserved in other organisms, suggesting that this collection of host factors can serve as a starting point for identifying host factors that influence LTR retroelements and retroviruses in other organisms. Overall, our data indicate that Ty1 requires a large number of cellular host factors to complete its retrotransposition cycle efficiently.
逆转录病毒及其亲属——长末端重复序列（LTR）逆转座子，在其宿主细胞内执行复杂的生命周期。我们利用了酿酒酵母基因组缺失项目开发的一系列基因缺失突变体，对影响酵母中逆转录病毒样Ty1元件的宿主因子进行功能基因组学筛选。通过对4483个纯合二倍体缺失菌株的分析，我们总共鉴定出了101个可能影响Ty1逆转座循环许多不同方面的基因。在这101个鉴定出的突变体中，46个的Ty1 cDNA水平发生了显著变化，而其余55个突变体的Ty1 cDNA水平正常。因此，大约一半的突变体显然影响了逆转座的早期阶段，直至病毒样颗粒的组装和cDNA复制，而其余一半则影响了cDNA复制后发生的步骤。虽然大多数突变体保留了将Ty1整合靶向tRNA基因的能力，但有2个突变体的tRNA基因靶向水平降低。在本研究中鉴定出的基因产物中，超过25%在其他生物体中是保守的，这表明这组宿主因子可作为鉴定影响其他生物体中LTR逆转元件和逆转录病毒的宿主因子的起点。总体而言，我们的数据表明，Ty1需要大量细胞宿主因子才能有效地完成其逆转座循环。
