Previous Article | Next Article ![]()
Mol. Cell. Biol., Nov 1995, 6406-6419, Vol 15, No. 11
JE Kalish, C Theda, JC Morrell, JM Berg and SJ Gould
We have cloned and sequenced PAS7, a gene required for peroxisome assembly
in the yeast Pichia pastoris. The product of this gene, Pas7p, is a member
of the C3HC4 superfamily of zinc-binding proteins. Point mutations that
alter conserved residues of the C3HC4 motif abolish PAS7 activity and
reduce zinc binding, suggesting that Pas7p binds zinc in vivo and that zinc
binding is essential for PAS7 function. As with most pas mutants, pas7
cells exhibit a pronounced deficiency in import of peroxisomal matrix
proteins that contain either the type 1 peroxisomal targeting signal (PTS1)
or the type 2 PTS (PTS2). However, while other yeast and mammalian pas
mutants accumulate ovoid, vesicular peroxisomal intermediates, loss of
Pas7p leads to accumulation of membrane sheets and vesicles which lack a
recognizable lumen. Thus, Pas7p appears to be essential for protein
translocation into peroxisomes as well as formation of the lumen of the
organelle. Consistent with these data, we find that Pas7p is an integral
peroxisomal membrane protein which is entirely resistant to exogenous
protease and thus appears to reside completely within the peroxisome. Our
observations suggest that the function of Pas7p defines a previously
unrecognized step in peroxisome assembly: formation of the peroxisome
lumen. Furthermore, because the peroxisomal intermediates in the pas7 delta
mutant proliferate in response to peroxisome-inducing environmental
conditions, we conclude that Pas7p is not required for peroxisome
proliferation.
Copyright © 1995, American Society for Microbiology
Formation of the peroxisome lumen is abolished by loss of Pichia pastoris Pas7p, a zinc-binding integral membrane protein of the peroxisome
Kennedy Krieger Research Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»