Brefeldin A inhibited activity of the sec7 domain of p200, a mammalian guanine nucleotide-exchange protein for ADP-ribosylation factors.
نویسندگان
چکیده
A brefeldin A (BFA)-inhibited guanine nucleotide-exchange protein (GEP) for ADP-ribosylation factors (ARF) was purified earlier from bovine brain cytosol. Cloning and expression of the cDNA confirmed that the recombinant protein (p200) is a BFA-sensitive ARF GEP. p200 contains a domain that is 50% identical in amino acid sequence to a region in yeast Sec7, termed the Sec7 domain. Sec7 domains have been identified also in other proteins with ARF GEP activity, some of which are not inhibited by BFA. To identify structural elements that influence GEP activity and its BFA sensitivity, several truncated mutants of p200 were made. Deletion of sequence C-terminal to the Sec7 domain did not affect GEP activity. A protein lacking 594 amino acids at the N terminus, as well as sequence following the Sec7 domain, also had high activity. The mutant lacking 630 N-terminal amino acids was, however, only 1% as active, as was the Sec7 domain itself (mutant lacking 697 N-terminal residues). It appears that the Sec7 domain of p200 contains the catalytic site but additional sequence (perhaps especially that between positions 595 and 630) modifies activity dramatically. Myristoylated recombinant ARFs were better than non-myristoylated as substrates; ARFs 1 and 3 were better than ARF5, and no activity was detected with ARF6. Physical interaction of the Sec7 domain with an ARF1 mutant was demonstrated, but it was much weaker than that of the cytohesin-1 Sec7 domain with the same ARF protein. Effects of BFA on p200 and all mutants with high activity were similar with approximately 50% inhibition at </=50 microM. The inactive BFA analogue B36 did not inhibit the Sec7 domain or p200. Thus, the Sec7 domain of p200, like that of Sec7 itself (Sata, M., Donaldson, J. G., Moss, J., and Vaughan, M. (1998) Proc. Natl. Acad. Sci. U. S. A. 95, 4204-4208), plays a role in BFA inhibition as well as in GEP activity, although the latter is markedly modified by other structural elements.
منابع مشابه
Brefeldin A-inhibited guanine nucleotide-exchange activity of Sec7 domain from yeast Sec7 with yeast and mammalian ADP ribosylation factors.
The Saccharomyces cerevisiae Sec7 protein (ySec7p), which is an important component of the yeast secretory pathway, contains a sequence of approximately 200 amino acids referred to as a Sec7 domain. Similar Sec7 domain sequences have been recognized in several guanine nucleotide-exchange proteins (GEPs) for ADP ribosylation factors (ARFs). ARFs are approximately 20-kDa GTPases that regulate int...
متن کاملp200 ARF-GEP1: a Golgi-localized guanine nucleotide exchange protein whose Sec7 domain is targeted by the drug brefeldin A.
The drug brefeldin A (BFA) disrupts protein traffic and Golgi morphology by blocking activation of ADP ribosylation factors (ARFs) through an unknown mechanism. Here, we investigated the cellular localization and BFA sensitivity of human p200 ARF-GEP1 (p200), a ubiquitously expressed guanine nucleotide exchange factor of the Sec7 domain family. Multiple tagged forms of the full-length polypepti...
متن کاملCloning and expression of a cDNA encoding a bovine brain brefeldin A-sensitive guanine nucleotide-exchange protein for ADP-ribosylation factor.
A 200-kDa guanine nucleotide-exchange protein (p200 or GEP) for ADP-ribosylation factors 1 and 3 (ARF1 and ARF3) that was inhibited by brefeldin A (BFA) was purified earlier from cytosol of bovine brain cortex. Amino acid sequences of four tryptic peptides were 47% identical to that of Sec7 from Saccharomyces cerevisiae, which is involved in vesicular trafficking in the Golgi. By using a PCR-ba...
متن کاملOn the action of Brefeldin A on Sec7-stimulated membrane-recruitment and GDP/GTP exchange of Arf proteins.
Arf (ADP-ribosylation factor) proteins form a special class of small GTP-binding proteins in that their activation by GDP/GTP exchange is coupled to their recruitment to membranes using a built-in structural mechanism. These coupled processes are stimulated by GEFs (guanine nucleotide-exchange factors) that carry a catalytic Sec7 domain, whose basic mechanism has been uncovered by biochemical a...
متن کاملN-terminal targeting of guanine nucleotide exchange factors (GEF) for ADP ribosylation factors (ARF) to the Golgi.
B2-1 (cytohesin-1) is a member of a group of proteins (including ARNO and ARNO3) that are all of similar size and domain composition. The three proteins contain an N-terminal coiled-coil domain, followed by a Sec7 and a pleckstrin homology (PH) domain. While it is well established that the Sec7 domain functions as a guanine nucleotide exchange factor (GEF) for ADP-ribosylation factors (ARFs) an...
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ورودعنوان ژورنال:
- The Journal of biological chemistry
دوره 274 25 شماره
صفحات -
تاریخ انتشار 1999