Department of Genetics, University of Melbourne, Parkville, Victoria, Australia.
Metallomics. 2010 Aug;2(8):556-64. doi: 10.1039/c003484c. Epub 2010 Jul 1.
A complete inventory of metallochaperone-like proteins containing a predicted HMA domain in Arabidopsis revealed a large family of 67 proteins. 45 proteins, the HIPPs, have a predicted isoprenylation site while 22 proteins, the HPPs, do not. Sequence comparisons divided the proteins into seven major clusters (I-VII). Cluster IV is notable for the presence of a conserved Asp residue before the CysXXCys, metal binding motif, analogous to the Zn binding motif in E. coli ZntA. HIPP20, HIPP21, HIPP22, HIPP26 and HIPP27 in Cluster IV were studied in more detail. All but HIPP21 could rescue the Cd-sensitive, ycf1 yeast mutant but failed to rescue the growth of zrt1zrt2, zrc1cot1 and atx1 mutants. In Arabidopsis, single and double mutants did not show a phenotype but the hipp20/21/22 triple mutant was more sensitive to Cd and accumulated less Cd than the wild-type suggesting the HIPPs can have a role in Cd-detoxification, possibly by binding Cd. Promoter-GUS reporter expression studies indicated variable expression of these HIPPs. For example, in roots, HIPP22 and HIPP26 are only expressed in lateral root tips while HIPP20 and HIPP25 show strong expression in the root vasculature.
在拟南芥中，对含有预测的 HMA 结构域的金属伴侣蛋白进行全面编目，揭示了一个由 67 种蛋白质组成的大家族。45 种蛋白质（HIPPs）具有预测的异戊烯基化位点，而 22 种蛋白质（HPPs）则没有。序列比较将这些蛋白质分为七个主要簇（I-VII）。IV 簇的特点是在 CysXXCys 金属结合基序之前存在保守的 Asp 残基，类似于大肠杆菌 ZntA 中的 Zn 结合基序。对 IV 簇中的 HIPP20、HIPP21、HIPP22、HIPP26 和 HIPP27 进行了更详细的研究。除了 HIPP21 之外，所有 HIPPs 都可以拯救 Cd 敏感的 ycf1 酵母突变体，但不能拯救 zrt1zrt2、zrc1cot1 和 atx1 突变体的生长。在拟南芥中，单突变体和双突变体没有表现出表型，但 hipp20/21/22 三重突变体对 Cd 更敏感，积累的 Cd 比野生型少，这表明 HIPPs 可能在 Cd 解毒中发挥作用，可能通过结合 Cd。启动子-GUS 报告基因表达研究表明这些 HIPPs 的表达存在差异。例如，在根中，HIPP22 和 HIPP26 仅在侧根尖端表达，而 HIPP20 和 HIPP25 在根脉管系统中表达强烈。
