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The peroxisomal membrane proteins of Candida boidinii: gene isolation and expression
M Moreno1, R Lark, K L Campbell
1Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235-9041.
Abstract:
Candida boidinii is a methylotrophic yeast in which several growth substrates can cause vigorous peroxisomal proliferation. While such diverse substrates as methanol, oleic acid and D-alanine induce different peroxisomal metabolic pathways, membranes seem to contain common abundant peroxisomal membrane proteins (PMPs). These proteins have been termed PMP31, PMP32 and PMP47. The gene encoding PMP47 has been previously cloned and analysed. We now report the isolation of a second PMP47 gene (or allele) as well as PMP31 and PMP32. PMP47A and PMP47B share 95% sequence identity at the amino acid level. PMP31 and PMP32 each contain 256 amino acids and are highly similar (97% identity) in protein sequence. Both PMP31 and PMP32 are predicted to span the membrane once or twice. All abundant PMPs of C. boidinii are basic in charge; they all have predicted isoelectric points above 10. RNAs corresponding to the PMP47s and to PMPs31-32 are strongly induced by methanol, oleic acid and D-alanine. While the PMP47s probably encode substrate carriers, the functions of PMP31 and PMP32 from C. boidinii are still unknown.
Insights
Researchers identified new genes for abundant peroxisomal membrane proteins (PMPs) in Candida boidinii. These PMPs are crucial for peroxisome proliferation in response to various growth substrates.
Area of Science:
- * Cell Biology
- * Molecular Biology
- * Biochemistry
Background:
- * Candida boidinii, a methylotrophic yeast, exhibits significant peroxisome proliferation in response to diverse growth substrates like methanol, oleic acid, and D-alanine.
- * Peroxisomal membranes contain common abundant proteins, including PMP31, PMP32, and PMP47, despite varied metabolic pathways induced by different substrates.
Purpose of the Study:
- * To isolate and characterize additional genes encoding abundant peroxisomal membrane proteins (PMPs) in Candida boidinii.
- * To investigate the sequence similarity, predicted structure, and expression patterns of these newly identified PMPs.
Main Methods:
- * Gene isolation and sequencing to identify PMP31, PMP32, and a second PMP47 allele (PMP47B).
- * Bioinformatic analysis to predict protein properties, including sequence identity and membrane spanning regions.
- * RNA analysis to determine gene expression levels in response to different growth substrates.
Main Results:
- * Isolation of a second PMP47 gene (PMP47B) and the genes for PMP31 and PMP32.
- * High sequence identity observed between PMP47A and PMP47B (95%), and between PMP31 and PMP32 (97%).
- * PMP31 and PMP32 are predicted to be basic proteins with one or two membrane-spanning domains.
- * Expression of PMP47s and PMPs31-32 is strongly induced by methanol, oleic acid, and D-alanine.
Conclusions:
- * Multiple genes encode abundant peroxisomal membrane proteins in Candida boidinii.
- * The PMP47 proteins likely function as substrate carriers.
- * The specific functions of PMP31 and PMP32 in Candida boidinii remain to be elucidated.