The gene fragment encoding the retinal protein from helix C to helix G in a new strain of halobacteria, H.sp.xz515 has been amplified by PCR method. The nucleotide sequence of this fragment has been determined. The de...The gene fragment encoding the retinal protein from helix C to helix G in a new strain of halobacteria, H.sp.xz515 has been amplified by PCR method. The nucleotide sequence of this fragment has been determined. The deduced amino acid sequence has been compared with halobium br and other two br-like proteins, ar-1 and ar-2. Results show that those amino acid residues in br, essential for proton pumping and binding to retinal, are conserved. The residue M145 in br may be important for isomerization reaction of retinal.展开更多
Halobacteria H.sp.xz 515 was isolated from a salt lake in Tibet. Although proton release-and-uptake across claret membrane is in reverse order compared to bacteri-orhodopsin in purple membrane from Halobacterium Sali-...Halobacteria H.sp.xz 515 was isolated from a salt lake in Tibet. Although proton release-and-uptake across claret membrane is in reverse order compared to bacteri-orhodopsin in purple membrane from Halobacterium Sali-narum, and its efficiency of proton pump is much lower, AFM image shows that the molecules are still arranged in a two-dimensional hexagonal lattice of trimers. Primary structure of C- to G-helix of the archaerhodopsin shows that it has only 56% homology with bacteriorhodopsin. But the interactive amino acid residues at the interface between B-and D-helixes are conserved. These amino acid residues are believed to play a significant role in the stability of protein oligomers.展开更多
古紫质-4(Archaerhodopsin-4,aR4)是一种存在于嗜盐菌Halobacterium species XZ515细胞膜上含有类胡萝卜素发色团菌红素(Bacterioruberin)的光敏受体蛋白,与细菌视紫红质(Bacteriorhodopsin,bR)具有相似的三聚结构和光驱质子泵功能。尽...古紫质-4(Archaerhodopsin-4,aR4)是一种存在于嗜盐菌Halobacterium species XZ515细胞膜上含有类胡萝卜素发色团菌红素(Bacterioruberin)的光敏受体蛋白,与细菌视紫红质(Bacteriorhodopsin,bR)具有相似的三聚结构和光驱质子泵功能。尽管二者均为外向质子泵,但aR4表现为与bR不同的先摄取后释放的质子传输时序。位于bR胞外半通道的精氨酸82(Arginine 82,R82)充当着视黄醛键合区五边形氢键网络与质子释放簇(proton release cluster,PRC)之间的桥梁,不仅向胞外传递D85的质子化信息,同时调控PRC质子的释放和再质子化。R83作为aR4中的同源等位残基,其侧链取向与bR中的R82有所不同,而这一差异是否与其质子释放时序的不同有关目前尚未见报道。为此,本研究采用定点突变技术、原位紫外-可见光吸收光谱、闪光动力学光谱、酸碱滴定等技术手段,对比分析R83和R82在aR4和bR中的差异性作用。研究表明,R83和R82在aR4和bR中均起到质子受体与质子释放簇之间的“桥梁”作用,但是R83与PRC间的氢键相互作用要弱于R82与PRC间的氢键相互作用,这可能是导致aR4不同质子释放时序的原因之一。此外,菌红素的缺失可导致R83功能对体系pH依赖性增加。展开更多
文摘The gene fragment encoding the retinal protein from helix C to helix G in a new strain of halobacteria, H.sp.xz515 has been amplified by PCR method. The nucleotide sequence of this fragment has been determined. The deduced amino acid sequence has been compared with halobium br and other two br-like proteins, ar-1 and ar-2. Results show that those amino acid residues in br, essential for proton pumping and binding to retinal, are conserved. The residue M145 in br may be important for isomerization reaction of retinal.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 19890385, 39730150 and 19725415) the key programs of the Chinese Academy of Sciences (Grant Nos.KJ951-A1-603, KJ951-A1-409, KJ952-J1-469 and STZ-00-07).
文摘Halobacteria H.sp.xz 515 was isolated from a salt lake in Tibet. Although proton release-and-uptake across claret membrane is in reverse order compared to bacteri-orhodopsin in purple membrane from Halobacterium Sali-narum, and its efficiency of proton pump is much lower, AFM image shows that the molecules are still arranged in a two-dimensional hexagonal lattice of trimers. Primary structure of C- to G-helix of the archaerhodopsin shows that it has only 56% homology with bacteriorhodopsin. But the interactive amino acid residues at the interface between B-and D-helixes are conserved. These amino acid residues are believed to play a significant role in the stability of protein oligomers.
