施氏假单胞菌固氮调控蛋白NifA调节电子传递体rnf1基因簇的表达

施氏假单胞菌A1501中电子传递体基因簇rnf1位于固氮基因岛上,该基因簇的突变造成固氮酶活显著下降。在rnf1基因簇的启动子区含有固氮调控蛋白NifA的保守结合序列,实时定量qRT-PCR分析证实了nifA突变株中rnf1基因簇的表达量与野生型相比急剧下调,暗示着NifA直接参与rnf1基因簇的表达调控。细菌单杂交系统的体内互作实验表明,在大肠杆菌体内NifA与rnf1基因簇启动子存在直接相互作用;进一步的凝胶阻滞试验证明原核表达纯化的NifA蛋白与rnf1基因簇启动子序列存在体外直接结合。上述结果从分子水平上给出了两者间相互作用的直接证据,为深入研究联合固氮基因的表达调控网络奠定了基础。     

Hemoglobin I mutation encoded at both alpha-globin loci on the same chromosome: concerted evolution in the human genome

Genetic analysis of an individual expressing an unexpectedly high level of hemoglobin I, an alpha-globin structural mutant, reveals that the mutation is present at both the alpha 1- and the alpha 2-globin gene loci. Kindred analysis confirms that the two affected genes are located in cis. The most likely explanation for this finding is that a recent conversion event occurred within the human alpha-globin gene cluster.     

玉米大斑病菌Homeobox转录因子家族全基因组鉴定及其表达规律分析

【目的】从全基因组水平上鉴定玉米大斑病菌(Setosphaeria turcica)Homeobox转录因子家族及其分布,阐明该家族的序列及进化特征,分析该家族基因在病菌不同生长发育时期的表达规律。【方法】利用生物信息学手段搜索玉米大斑病菌全基因组数据库,鉴定Homeobox转录因子家族;采用MEGA 5.0软件进行系统进化树分析;利用在线工具GSDS(gene structure display server)(http://gsds1.cbi.pku.edu.cn/index.php)绘制基因结构图;利用Clustal X 1.83软件分析Homeobox保守结构域(HOX保守结构域)的氨基酸序列特征;利用SOPMA(https://npsa-prabi.ibcp.fr/cgi-bin/npsa_automat.plpage=npsa_sopma.html)对Homeobox蛋白的二级结构进行在线预测;利用实时荧光定量PCR(q RT-PCR)技术分析Homeobox转录因子家族在病菌不同发育时期的表达模式。【结果】在玉米大斑病菌中鉴定了8个Homeobox转录因子家族成员(St HTF1-8),根据基因结构及系统进化特征将其分为4类;亚细胞定位预测分析表明,这8个蛋白全部定位在细胞核中;该家族成员均含有HOX保守结构域,其二级结构具有特征性的"螺旋-转角-螺旋"(helix-turn-helix)结构;利用q RT-PCR技术对该家族成员在菌丝、分生孢子形成、芽管形成、附着胞及侵入丝形成等5个时期的表达规律分析,发现不同基因在病菌不同发育时期具有不同的表达水平,其中St HTF1在菌丝发育、分生孢子及附着胞形成等3个时期的表达水平相对较高,St HTF3、St HTF4在分生孢子形成时期表达水平最高,St HTF6在芽管形成时期的表达水平最高,St HTF2、St HTF5、St HTF7和St HTF8在附着胞形成时期的表达水平均较高。【结论】玉米大斑病菌包括Homeobox转录因子家族包含8个成员,在进化上分为4大类,全部成员均分布在细胞核内,其编码蛋白质均含有保守的HOX结构域及"螺旋-转角-螺旋"空间结构;该基因家族成员在病菌不同发育时期呈现不同的表达规律。     

Location of gene for beta subunit of human T-cell receptor at band 7q35, a region prone to rearrangements in T cells

The T-cell receptor is formed by two chains, alpha and beta, for which specific clones were recently obtained. In this report the gene for the beta chain of the human T-cell receptor was located on the long arm of chromosome 7, band q35, by means of in situ hybridization. This chromosome region in T cells is unusually prone to develop breaks in vivo, perhaps reflecting instability generated by somatic rearrangement of T-cell receptor genes during normal differentiation in this cell lineage.     

The BRCT domain is a phospho-protein binding domain

The carboxyl-terminal domain (BRCT) of the Breast Cancer Gene 1 (BRCA1) protein is an evolutionarily conserved module that exists in a large number of proteins from prokaryotes to eukaryotes. Although most BRCT domain-containing proteins participate in DNA-damage checkpoint or DNA-repair pathways, or both, the function of the BRCT domain is not fully understood. We show that the BRCA1 BRCT domain directly interacts with phosphorylated BRCA1-Associated Carboxyl-terminal Helicase (BACH1). This specific interaction between BRCA1 and phosphorylated BACH1 is cell cycle regulated and is required for DNA damage-induced checkpoint control during the transition from G2 to M phase of the cell cycle. Further, we show that two other BRCT domains interact with their respective physiological partners in a phosphorylation-dependent manner. Thirteen additional BRCT domains also preferentially bind phospho-peptides rather than nonphosphorylated control peptides. These data imply that the BRCT domain is a phospho-protein binding domain involved in cell cycle control.     

Selective trafficking of non-cell-autonomous proteins mediated by NtNCAPP1

In plants, cell-to-cell communication is mediated by plasmodesmata and involves the trafficking of non-cell-autonomous proteins (NCAPs). A component in this pathway, Nicotiana tabacum NON-CELL-AUTONOMOUS PATHWAY PROTEIN1 (NtNCAPP1), was affinity purified and cloned. Protein overlay assays and in vivo studies showed that NtNCAPP1 is located on the endoplasmic reticulum at the cell periphery and displays specificity in its interaction with NCAPs. Deletion of the NtNCAPP1 amino-terminal transmembrane domain produced a dominant-negative mutant that blocked the trafficking of specific NCAPs. Transgenic tobacco plants expressing this mutant form of NtNCAPP1 and plants in which the NtNCAPP1 gene was silenced were compromised in their ability to regulate leaf and floral development. These results support a model in which NCAP delivery to plasmodesmata is both selective and regulated.     

玉米大斑病菌转录因子StSte12的活性及其对酵母生长的功能互补分析

【目的】分析玉米大斑病菌StSte12的结构、转录活性及功能。【方法】利用生物信息学方法,对获得的StSte12进行保守结构域和进化树分析,推测该基因的功能;利用β-半乳糖苷酶法检测StSte12的转录活性;将StSTE12转化至酿酒酵母ScSTE12基因缺失突变体ste12Δ中,筛选酿酒酵母ScSTE12的功能互补突变体并对其分析,验证玉米大斑病菌StSTE12的功能。【结果】通过蛋白比对发现StSte12具有转录因子特有的STE homeodomain和ZnF_C2H2锌指结构;同源性分析显示,该基因与其它植物病原真菌的STE12-like基因有较高的同源性;利用β-半乳糖苷酶法检测发现,StSte12具有转录激活活性;酵母互补试验表明,StSTE12可以回复酿酒酵母ste12Δ的功能,能够调控酵母细胞的生长。【结论】玉米大斑病菌StSTE12属于STE12-like基因;转录因子StSte12具有转录活性;对酵母细胞在YPD培养基上的侵入生长有重要的调控作用。     

水稻dirigent基因家族生物信息学分析

摘　要：利用现有的水稻生物信息资源,共鉴定出了53个水稻dirigent (OsDIR)基因,它们分布在8条水稻染色体上;基因结构分析显示,有32个OsDIR基因不含内含子,占总数的60.4%;保守功能区域预测表明,OsDIR基因至少含有1个保守的DIR功能域;模块预测显示,水稻DIR蛋白拥有至少10个大小不同的保守模块,且不同模块在基因家族成员中出现的频率有较大的差异;蛋白序列比对表明,该基因家族蛋白保守序列均位于DIR功能域内;蛋白功能预测表明,大多数OsDIR蛋白为稳定的疏水性蛋白,表达于大多数细胞器中,且在细胞壁中表达最为丰富;同源基因分子遗传进化分析表明,OsDIR基因可分为5个亚类,功能域片段与基因的复制特征表明,OsDIR基因可能起源于共同的祖先(基因)。     

小鼠胚胎干细胞核心转录因子nanog靶基因Zbtb9的生物信息学分析

通过特异性引物用RT-PCR方法扩增Zbtb9基因。利用生物信息学对小鼠的Zbtb9基因启动子进行生物信息学分析,预测Zbtb9基因启动子位置和启动子区内含有的转录因子结合位点,以及nanog在Zbtb9基因转录调控中的作用及Zbtb9蛋白的基本性质。Zbtb9基因启动子区可能定位于转录起始点上游790 bp至1024 bp之间。启动子区内含有15个转录调控因子结合位点,nanog的作用靶序列位于Zbtb9基因启动子区与转录起始位点之间,提示nanog在Zbtb9基因转录调控中起作用,小鼠Zbtb9蛋白二级结构可能以螺旋为主,富含疏水性氨基酸;对Zbtb9基因疏水区的氨基酸进行跨膜区分析,提示可能是跨膜蛋白。经SMART分析,Zbtb9蛋白含有BTB/POZ结构域。