CHROMOSOME STURCTURE IN <I>E. COLI</I> AND <I>SCHIZOSACCHAROMYCES POMBE</I>

高阶染色质结构在许多细胞过程中起着重要作用，包括基因调控、细胞类型确定和染色体遗传。我们已经发现，我们可以使用有毒物质樟脑来破坏染色质结构。樟脑在体内和体外都能使染色体解聚。我们已经在大肠杆菌和裂殖酵母中使用樟脑来分离基因，当过度生产时，这些基因赋予细胞樟脑抗性。在大肠杆菌中，樟脑抗性鉴定出一个三基因系统。CRCA改变外膜的通透性，使其具有部分的樟脑抗性。CSPE是一种类似冷休克的蛋白，而CrcB是一种预测的疏水蛋白，它们与染色体凝聚和对樟脑的完全抗性有关。我们已经证明，无论是在体内还是在体外，这三个基因的过度生产都会导致更紧密的凝聚类核。如果我们单独过度生产CSPE，我们可以表现出部分樟脑抗性和类核凝聚。CSPE与单链DNA、双链DNA和信使RNA结合。我们已经在CSPE中发现了能够仅结合dsDNA或仅能结合单链核酸的突变。那些与dsDNA结合的突变体仍然能够凝聚染色体，而单链核酸结合突变体则不能。我们目前正在努力了解CSPE是如何通过与dsDNA结合来浓缩染色体的。在S.pombe中，我们发现樟脑抗性可能是组蛋白脱乙酰酶Clr3和Clr6过度产生的结果。已知这两种蛋白质都影响高阶染色质结构，并需要沉默交配型基因座的DNA。樟脑选择还鉴定了几个新基因，其中约三分之一的基因还减少了交配型沉默并影响了染色体的稳定性。我们目前正在研究这些基因的性质和功能。综上所述，我们使用樟脑作为染色质结构的探针。这些研究将使我们能够确定高阶染色质结构是如何形成和保持的，从而使完整和完全功能的染色体能够被子代细胞遗传。-细菌遗传学，染色体凝集，大肠杆菌，裂殖酵母遗传学，高阶染色质结构，裂殖酵母，庞氏裂殖酵母，-非人类受试者或人类组织

Higher order chromatin structure plays a vital role in many cellular processes including, gene regulation, cell type determination and chromosome inheritance. We have found that we can disrupt chromatin structure using the toxic agent, camphor. Camphor decondenses chromosomes both in vivo and in vitro. We have used camphor in both Escherichia coli and Schizosaccharomyces pombe to isolate genes, which when overproduced confer camphor resistance on cells. In E. coli, camphor resistance identified a three gene system. CrcA alters the permeability of the outer membrane to give partial camphor resistance. CspE, a cold-shock-like protein, and CrcB, a predicted hydrophobic protein, are responsible for chromosome condensation and complete camphor resistance. We have demonstrated that, both in vivo and in vitro, overproduction of the three genes results in more tightly condensed nucleoids. If we overproduce CspE alone, we can demonstrate partial camphor resistance and nucleoid condensation. CspE binds to single-stranded DNA, double-stranded DNA and messenger RNA. We have identified mutations in CspE that are capable of binding only dsDNA or only single stranded nucleic acids. Those that bind dsDNA are still capable of chromosome condensation, whereas single stranded nucleic acid binding mutants do not. We are currently working to understand how CspE condenses the chromosome through binding to dsDNA.In S.pombe, we have found that camphor resistance can result from overproduction of the histone deacetylases, Clr3 and Clr6. Both of these proteins are known to affect the higher order chromatin structure and to be required for silencing of the DNA of the mating type loci. The camphor selection has also identified several novel genes, with approximately one third of them also decreasing mating type silencing and affecting chromosome stability. We are currently investigating the nature and function of these genes.In summary, we are using camphor as a probe of chromatin structure. These studies will allow us to determine how higher-order chromatin structure is formed and maintained, thus allowing intact and fully functional chromosomes to be inherited by daughter cells. - Bacterial genetics, chromosome condensation, Escherichia coli, Fission Yeast Genetics, Higher Order Chromatin Sturcture, Schizosaccharomyces pombe, - Neither Human Subjects nor Human Tissues