Srikarthika Jambunathan, Joseph D. Fontes
Sumoylation of the zinc finger protein ZXDC enhances the function of its transcriptional activation domain
The transcription of major histocompatibility complex class II (MHC II) genes is dependent
upon the co-activator protein class II trans-activator (CIITA). We have recently identified a
protein known as zinc finger X-linked duplicated family member C (ZXDC) that, along with
its binding partner ZXDA, forms a complex that interacts with CIITA and regulates MHC II
transcription. Western analysis with anti-ZXDC antibodies identified two species of the ZXDC
protein, one migrating near its predicted molecular mass and one with slower electrophoretic
mobility. We report here that the slower migrating form is the result of sumoylation at a single
lysine residue within the transcriptional activation domain of ZXDC. Three SUMO proteins
(SUMO-1, -2 and -3) can modify the ZXDC protein. Multiple SUMO E3 ligase enzymes and
HDAC4 can facilitate ZXDC sumoylation, and one ligase, PIASy, interacted with a specific
region of the ZXDC protein. We found that sumoylation does not appear to disrupt or modulate
the interaction of ZXDC with its binding partners. Rather, sumoylation of ZXDC is required
for full activity of the transcriptional activation domain. Our findings suggest that sumoylation
is an important regulator of ZXDC.
Biological Chemistry, Walter de Gruyter
Print ISSN: 1431-6730
Volume: 2007
Pages: -
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