572 / 2019-04-02 20:13:05

N-terminal acetylation stabilizes Arabidopsis SIGMA FACTOR BINDING PROTEIN 1 involved in salicylic acid-primed cell death

SIGMA FACTOR BINDING PEOTEIN 1 (SIB1), N-terminal acetylation (NTA), N-terminal acetyltransferase (NAT), Protein stability, Ac/N-end rule pathway

全体主题 > Abiotic Stress

N-terminal (Nt) acetylation (NTA) is one of the most abundant, irreversible and a co-translational protein modification, which is catalyzed by ribosome-associated N-terminal acetyltransferases (NATs). NTA acting as an Nt degradation signal (Ac/N-degron) for proteolysis has been established to a large extent in yeast and mammals, referred to as Nt-acetylation-targeted N-end rule pathway (Ac/N-end rule pathway). However, the biological relevance of the NTA remained obscure in plants. In this study, we found that SIB1, a transcriptional co-regulator, undergoes an absolute NTA on the initiator methionine (iMet). On the contrary to yeast and mammals, our genetic and biochemical analysis revealed that NTA on SIB1 via N-acetyltransferase B complex (NatB) stabilizes SIB1 protein. Accordingly, the NTA-conferred stability ensures the activation of SIB1-dependent gene expression. Here we disclose SIB1 as a bona-fide substrate of NatB and its NTA largely contributes to the SA-primed cell death response.