The SUMO E3 Ligase-Like Proteins PIAL1 and PIAL2 Interact with MOM1 and Form a Novel Complex Required for Transcriptional Silencing.
The mechanism by which MORPHEUS' MOLECULE1 (MOM1) contributes to transcriptional gene silencing has remained elusive since the gene was first identified and characterized. Here, we report that two Arabidopsis thaliana PIAS (PROTEIN INHIBITOR OF ACTIVATED STAT)-type SUMO E3 ligase-like proteins, PIAL1 and PIAL2, function redundantly to mediate transcriptional silencing at MOM1 target loci. PIAL1 and PIAL2 physically interact with each other and with MOM1 to form a high molecular mass complex. In the absence of either PIAL2 or MOM1, the formation of the high molecular mass complex is disrupted. We identified a previously uncharacterized IND (interacting domain) in PIAL1 and PIAL2 and demonstrated that IND directly interacts with MOM1. The CMM2 (conserved MOM1 motif 2) domain of MOM1 was previously shown to be required for the dimerization of MOM1. We demonstrated that the CMM2 domain is also required for the interaction of MOM1 with PIAL1 and PIAL2. We found that although PIAL2 has SUMO E3 ligase activity, the activity is dispensable for PIAL2's function in transcriptional silencing. This study suggests that PIAL1 and PIAl2 act as components of the MOM1-containing complex to mediate transcriptional silencing at heterochromatin regions.
National Institute of Biological Sciences, Beijing 102206, China.
Yong-Feng
0000-0002-5626-668X
YF
Han
National Institute of Biological Sciences, Beijing 102206, China Graduate School of Peking Union Medical College, Beijing 100730, China.
Qiu-Yuan
0000-0002-0295-3513
QY
Zhao
National Institute of Biological Sciences, Beijing 102206, China.
Liang-Liang
LL
Dang
National Institute of Biological Sciences, Beijing 102206, China.
Yu-Xi
YX
Luo
National Institute of Biological Sciences, Beijing 102206, China.
Shan-Shan
SS
Chen
National Institute of Biological Sciences, Beijing 102206, China.
Chang-Rong
CR
Shao
National Institute of Biological Sciences, Beijing 102206, China.
Huan-Wei
HW
Huang
National Institute of Biological Sciences, Beijing 102206, China.
Yong-Qiang
YQ
Li
National Institute of Biological Sciences, Beijing 102206, China.
Lin
L
Li
National Institute of Biological Sciences, Beijing 102206, China.
Tao
T
Cai
National Institute of Biological Sciences, Beijing 102206, China.
She
S
Chen
National Institute of Biological Sciences, Beijing 102206, China Graduate School of Peking Union Medical College, Beijing 100730, China hexinjian@nibs.ac.cn.
Xin-Jian
0000-0002-2878-7461
XJ
He
D000074183:ATPases Associated with Diverse Cellular Activities; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; D000074183:ATPases Associated with Diverse Cellular Activities; C409208:MOM protein, Arabidopsis