The Redox Biochemistry of Protein Sulfenylation and Sulfinylation

Controlled generation of reactive oxygen species orchestrates numerous physiological signaling events (Finkel, T. (2011) Signal transduction by reactive oxygen species. J. Cell Biol. 194, 7–15). A major cellular target of reactive oxygen species is the thiol side chain (RSH) of Cys, which may assume a wide range of oxidation states (i.e. −2 to +4). Within this context, Cys sulfenic (Cys-SOH) and sulfinic (Cys-SO₂H) acids have emerged as important mechanisms for regulation of protein function. Although this area has been under investigation for over a decade, the scope and biological role of sulfenic/sulfinic acid modifications have been recently expanded with the introduction of new tools for monitoring cysteine oxidation in vitro and directly in cells. This minireview discusses selected recent examples of protein sulfenylation and sulfinylation from the literature, highlighting the role of these post-translational modifications in cell signaling.     

UHRF2, a Ubiquitin E3 Ligase,Acts as a Small Ubiquitin-like Modifier E3 Ligase for Zinc Finger Protein 131

Small ubiquitin-like modifier (SUMO), a member of the ubiquitin-related protein family, is covalently conjugated to lysine residues of its substrates in a process referred to as SUMOylation. SUMOylation occurs through a series of enzymatic reactions analogous to that of the ubiquitination pathway, resulting in modification of the biochemical and functional properties of substrates. To date, four mammalian SUMO isoforms, a single heterodimeric SUMO-activating E1 enzyme SAE1/SAE2, a single SUMO-conjugating E2 enzyme ubiquitin-conjugating enzyme E2I (UBC9), and a few subgroups of SUMO E3 ligases have been identified. Several SUMO E3 ligases such as topoisomerase I binding, arginine/serine-rich (TOPORS), TNF receptor-associated factor 7 (TRAF7), and tripartite motif containing 27 (TRIM27) have dual functions as ubiquitin E3 ligases. Here, we demonstrate that the ubiquitin E3 ligase UHRF2 also acts as a SUMO E3 ligase. UHRF2 effectively enhances zinc finger protein 131 (ZNF131) SUMOylation but does not enhance ZNF131 ubiquitination. In addition, the SUMO E3 activity of UHRF2 on ZNF131 depends on the presence of SET and RING finger-associated and nuclear localization signal-containing region domains, whereas the critical ubiquitin E3 activity RING domain is dispensable. Our findings suggest that UHRF2 has independent functional domains and regulatory mechanisms for these two distinct enzymatic activities.     

长叶车前花叶病毒(HRV_(sh))外壳蛋白赖氨酸残基的修饰

我们曾报道长叶车前花叶病毒上海分离株(简称HRVsh)的外壳蛋白有二个赖氨酸残基,在PH8.5无变性剂存在的条件下,完整病毒颗粒表面的赖氨酸残基可与三硝基苯磺酸(TNPS)起反应,反应后的TNP-HRVsh病毒颗粒的感染力丧失达90％以上。 本文又进行了甲基乙亚胺甲酯(MEI)对HRVsh赖氨酸残基的修饰反应,修饰后的MEI-HRVsh病毒颗粒的感染力也同样丧失90％以上。 从三硝基苯磺酸修饰的病毒颗粒(TNP-HRVsh)中分离得到的RNA能与天然的HRVsh的外壳蛋白重建病毒颗粒,并具有感染力,说明修饰过程中核酸并不受影响。 进一步用同位素~(35)S,~(32)P双标记病毒,再以TNPS修饰标记的病毒,得到(~(35)S,~(32)P)-HRVsh及TNP-(~(35)S,~(32)P)-HRVsh。将两者分别接种于系统寄主青菜(Brassica chinensis)的一片叶片,一天后在非接种叶片上都可测得~(35)S,~(32)P的放射计数。其中,(~(35)S,~(32)P)-HRVsh的~(35)S/~(32)P比值降低了,而TNP-(~(35)S,~(32)P)-HRVsh的~(35)S/~(32)P比值保持不变。说明HRVsh外壳蛋白赖氨酸残基的修饰并不影响病毒颗粒进入寄主细胞,以及在寄主细胞间的转移。同位素双标记的结果表明,其感染力丧失的原因可能是由于上述修饰作用阻止了病毒在感染中所必须的脱壳过程。     

肝素修饰尿激酶某些性质的研究

本文对比研究了溴化氰活化及高碘酸活化肝素修饰的两种修饰尿激酶的性质。结果表明尿激酶在溴化氰活化肝素(肝素CN),高碘酸钠活化肝素(肝素I_4)的共价修饰后,其残余自由氨基分别是64％和52％;酶活性分别保留94％和90％;抗胃蛋白酶水解以及抗冻融变性的能力均高于天然酶;在离体血浆中的失活速变低于天然酶。本文还对修饰酶进行了萤光及紫外差光谱的分析,讨论了修饰过程对构象的影响。     

天冬酰胺酶及PEG_2-天冬酰胺酶对L-天冬酰胺、谷氨酰胺亲和性的研究

本文报导了天冬酰胺酶及PEG_2-天冬酰胺酶对废物L-天冬酰胺、谷氨酰胺亲和性的研究,结果表明:PEG_2-天冬酰胺酶对谷氨酰胺的亲和性明显强于天冬酰胺酶(Km值分别为7.35×10~(-3)mol/L和7.14×10~(-2)mol/L),对天冬酰胺的亲和性略强于天冬酰胺酶(Km值分别为2.9×10~(-5)mol/L和4.0×10~(-5)mol/L)。天冬酰胺酶和PEG_2-天冬酰胺酶的CD光谱表明:天冬酰胺和谷氨酰胺对天冬酰胺酶和PEG_2-天冬酰胺酶的构象影响较大,但天冬酰胺酶和PEG_2-天冬酰胺酶的构象变化趋势有明显的不同。     

Analysis of the effect of transplantation on morphometric and meristic characters in lake populations of the rainbow smelt,Osmerus mordax (Mitchill)

Synopsis Results of experimental transfer of rainbow smelt into lakes reclaimed by rotenone around 1960 in Maine were originally interpreted to cast doubt on the previously widely accepted hypothesis that there were two hereditarily different forms of rainbow smelt, one large and one small. Study of more recent data from some of the transplanted populations and reanalysis of the original data suggests different conclusions. The initial effect of introductions into a reclaimed lake may be accelerated and/or more prolonged growth which exceeds even interlake differences. This initial phase, however, is followed by a second phase, when the population reaches equilibrium and these effects subside. Data from phase two of the Little Concord-Shagg and Cold Stream-Coleback Lake transfers showed that the growth characteristics of the transplanted populations returned to those of the parental populations. Large differences in growth patterns were thus found only in the initial phase of the introduction. Meristic characters were little affected by transplanting.Analysis of large specimens derived from a postulated second unofficial introduction into Coleback Lake showed that they also differed significantly, having both higher gill raker and vertebral counts than the smaller smelt. This was of interest as smelt vertebral and gill raker counts usually are inversely related; hence we do not equate these for the moment with the large form of smelt known elsewhere.It is concluded that the initial interpretation of transfer experiments be delayed until conditions approaching equilibrium can be expected to exist. Further, our analysis of more recent lake transfer data has shown nothing to refute the hypothesis that there are at least two hereditarily different forms of smelt.     

化学修饰提高胰岛素口服降血糖作用的研究

本文探索了用小分子化合物对胰岛素进行化学修饰,以增加口服降血糖的可能性.制备了乙酰胰岛素、琥珀酰胰岛素和半乳糖酰胰岛素.这些胰岛素不仅较好地保持了天然胰岛素的活性,而且其口服降血糖作用也较天然胰岛素明显增加,其中琥珀酰胰岛素是天然胰岛素的口服降血糖作用的二倍以上.这为口服或肛门给药的胰岛素新剂型的研制提供了科学依据.     

N-tosyl-L-phenylalanylchloromethane reacts with cysteine 81 in the molecule of elongation factor Tu from Escherichia coli

Elongation factor EF-Tu from Escherichia coli was labelled with N-[¹⁴C]tosyl-L-phenylalanylchloromethane, digested with trypsin and the peptides obtained separated by HPLC. The only radioactive peak recovered corresponded to tryptic peptide containing residues 75–98. Sequencing of the peptide by automated Edman degradation identified cysteine 81 as the site of N-tosyl-L-phenylalanylchloromethane modification. These results confirm the importance of this residue for the interaction with aminoacyl-tRNAs.     

Influence du traitement sylvicole sur la flore forestiere: Cas de la futaie et du taillis-sous-futaie

Summary In a previous study, 772 floristics relevés, made in a large forest on calcareous soils (north-east France), had been treated by factorial analysis of correspondences in order to establish a site typology. The third axis separated chiefly Fagus and Quercus, which are very common in the forest, and various other ligneous or herbaceous species (see fig. 1). Two groups of relevés, homogeneous as for edaphic conditions, were choosen, having a significant position on this axis (with either positive or negative values). From this, floristic tables have been elaborated; they show clearly the influence of silvi culture (here high forest or coppice-with-standards) on part of both ligneous and herbaceous flora. Considering plant sociology, it appears that treating a stand as a coppice-with-standards can convert a Melico-Fagetum typicum (Eu-Fagion) into a Querceto Carpinetum typicum (Fraxino-Carpinion), and a Carici-Fagetum (Cephalanthero-Fagion) into a Querceto-Carpinetum primuletosum (Fraxino-Carpinion). Fortunately a large number of species are not influenced by the silviculture; this allows the identification of isopotential sites. Possible ecological causes are briefly discussed.

Nomenclature suivant: P. Fournier, 1961. Les quatre flores de France. Edition P. Le Chevalier, Paris. 1154 p.