TY - JOUR
T1 - A conserved cysteine is essential for Pex4p-dependent ubiquitination of the peroxisomal import receptor Pex5p
AU - Williams, Chris
AU - van den Berg, Marlene
AU - Sprenger, Richard R
AU - Distel, Ben
PY - 2007/8/3
Y1 - 2007/8/3
N2 - The peroxisomal protein import receptor Pex5p is modified by ubiquitin, both in an Ubc4p-dependent and -independent manner. Here we show that the two types of ubiquitination target different residues in the NH(2)-terminal region of Pex5p and we identify Pex4p (Ubc10p) as the ubiquitin-conjugating enzyme required for Ubc4p-independent ubiquitination. Whereas Ubc4p-dependent ubiquitination occurs on two lysine residues, Pex4p-dependent ubiquitination neither requires lysine residues nor the NH(2)-terminal alpha-NH(2) group. Instead, a conserved cysteine residue appears to be essential for both the Pex4p-dependent ubiquitination and the overall function of Pex5p. In addition, we show that this form of ubiquitinated Pex5p is susceptible to the reducing agent beta-mercaptoethanol, a compound that is unable to break ubiquitin-NH(2) group linkages. Together, our results strongly suggest that Pex4p-dependent ubiquitination of Pex5p occurs on a cysteine residue.
AB - The peroxisomal protein import receptor Pex5p is modified by ubiquitin, both in an Ubc4p-dependent and -independent manner. Here we show that the two types of ubiquitination target different residues in the NH(2)-terminal region of Pex5p and we identify Pex4p (Ubc10p) as the ubiquitin-conjugating enzyme required for Ubc4p-independent ubiquitination. Whereas Ubc4p-dependent ubiquitination occurs on two lysine residues, Pex4p-dependent ubiquitination neither requires lysine residues nor the NH(2)-terminal alpha-NH(2) group. Instead, a conserved cysteine residue appears to be essential for both the Pex4p-dependent ubiquitination and the overall function of Pex5p. In addition, we show that this form of ubiquitinated Pex5p is susceptible to the reducing agent beta-mercaptoethanol, a compound that is unable to break ubiquitin-NH(2) group linkages. Together, our results strongly suggest that Pex4p-dependent ubiquitination of Pex5p occurs on a cysteine residue.
U2 - 10.1074/jbc.M702038200
DO - 10.1074/jbc.M702038200
M3 - Journal article
C2 - 17550898
SN - 0021-9258
VL - 282
SP - 22534
EP - 22543
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 31
ER -