Bosco Daryl A, Eisenmesser Elan Z, Pochapsky Susan, Sundquist Wesley I, Kern Dorothee
Department of Biochemistry, Brandeis University, Waltham, MA 02454, USA.
Proc Natl Acad Sci U S A. 2002 Apr 16;99(8):5247-52. doi: 10.1073/pnas.082100499. Epub 2002 Apr 2.
Packaging of cyclophilin A (CypA) into HIV-1 virions is essential for efficient replication; however, the reason for this is unknown. Incorporation is mediated through binding to the Gly-89-Pro-90 peptide bond of the N-terminal domain of HIV-1 capsid (CA(N)). Despite the fact that CypA is a peptidyl-prolyl cis/trans isomerase, catalytic activity on CA(N) has not been observed previously. We show here, using NMR exchange spectroscopy, that CypA does not only bind to CA(N) but also catalyzes efficiently the cis/trans isomerization of the Gly-89-Pro-90 peptide bond. In addition, conformational changes in CA(N) distal to the CypA binding loop are observed on CypA binding and catalysis. The results provide experimental evidence for efficient CypA catalysis on a natively folded and biologically relevant protein substrate.
亲环蛋白A（CypA）包装进HIV-1病毒粒子对于高效复制至关重要；然而，其原因尚不清楚。这种掺入是通过与HIV-1衣壳N端结构域（CA(N)）的甘氨酸89-脯氨酸90肽键结合介导的。尽管CypA是一种肽基脯氨酰顺/反异构酶，但此前尚未观察到其对CA(N)的催化活性。我们在此利用核磁共振交换光谱表明，CypA不仅与CA(N)结合，还能高效催化甘氨酸89-脯氨酸90肽键的顺/反异构化。此外，在CypA结合和催化时，观察到CA(N)中远离CypA结合环的构象变化。这些结果为CypA对天然折叠且具有生物学相关性的蛋白质底物进行高效催化提供了实验证据。
