The promoter of filamentation (POF1) protein from Saccharomyces cerevisiae is an ATPase involved in the protein quality control process

Abstract

BackgroundThe gene YCL047C, which has been renamed promoter of filamentation gene (POF1), has recently been described as a cell component involved in yeast filamentous growth. The objective of this work is to understand the molecular and biological function of this gene.ResultsHere, we report that the protein encoded by the POF1 gene, Pof1p, is an ATPase that may be part of the Saccharomyces cerevisiae protein quality control pathway. According to the results, Δpof1 cells showed increased sensitivity to hydrogen peroxide, tert-butyl hydroperoxide, heat shock and protein unfolding agents, such as dithiothreitol and tunicamycin. Besides, the overexpression of POF1 suppressed the sensitivity of Δpct1, a strain that lacks a gene that encodes a phosphocholine cytidylyltransferase, to heat shock. In vitro analysis showed, however, that the purified Pof1p enzyme had no cytidylyltransferase activity but does have ATPase activity, with catalytic efficiency comparable to other ATPases involved in endoplasmic reticulum-associated degradation of proteins (ERAD). Supporting these findings, co-immunoprecipitation experiments showed a physical interaction between Pof1p and Ubc7p (an ubiquitin conjugating enzyme) in vivo.ConclusionsTaken together, the results strongly suggest that the biological function of Pof1p is related to the regulation of protein degradation.

YCL047C/POF1 Is a Novel Nicotinamide Mononucleotide Adenylyltransferase (NMNAT) in Saccharomyces cerevisiae

“…We also examined how POF1 deletion might affect cellular fitness. In line with the observation by Costa et al (21), deleting POF1 in qns1⌬ cells conferred sensitivity to H 2 O 2 , which was partially rescued by supplementing a higher concentration of NR (Fig. 4C).…”

“…In yeast, Nma1 and Nma2 have been shown to alleviate proteotoxicity in yeast models of proteinopathies (38). Studies by Costa et al (21) suggested that Pof1 has a role in protein quality control. Their study also showed that pof1⌬ exhibited compromised resistance to oxidative stress, heat shock, and chemicalinduced ER stress.…”

“…Pof1 was previously reported to harbor ATPase activity, which might be involved in protein quality control (21). Although the amino acid sequence of Pof1 does not show significant overall homology with any characterized protein, Pof1 possesses the characteristics of NMNAT.…”