Identification and Characterization of Tomato SWI3-Like Proteins: Overexpression of SlSWIC Increases the Leaf Size in Transgenic Arabidopsis.

Zhongyi Zhao,Songguang Yang,Tao Li,Keqiang Wu,Xiuling Peng

doi:10.3390/ijms20205121

Abstract

As the subunits of the SWI/SNF (mating-type switching (SWI) and sucrose nonfermenting (SNF)) chromatin-remodeling complexes (CRCs), Swi3-like proteins are crucial to chromatin remodeling in yeast and human. Growing evidence indicate that AtSWI3s are also essential for development and response to hormones in Arabidopsis. Nevertheless, the biological functions of Swi3-like proteins in tomato (Solanum lycopersicum) have not been investigated. Here we identified four Swi3-like proteins from tomato, namely SlSWI3A, SlSWI3B, SlSWI3C, and SlSWI3D. Subcellular localization analysis revealed that all SlSWI3s are localized in the nucleus. The expression patterns showed that all SlSWI3s are ubiquitously expressed in all tissues and organs, and SlSWI3A and SlSWI3B can be induced by cold treatment. In addition, we found that SlSWI3B can form homodimers with itself and heterodimers with SlSWI3A and SlSWI3C. SlSWI3B can also interact with SlRIN and SlCHR8, two proteins involved in tomato reproductive development. Overexpression of SlSWI3C increased the leaf size in transgenic Arabidopsis with increased expression of GROWTH REGULATING FACTORs, such as GRF3, GRF5, and GRF6. Taken together, our results indicate that SlSWI3s may play important roles in tomato growth and development.

Highlights

The fundamental unit of chromatin is the nucleosome, which is composed of two turns of DNA wrapped around a histone octamer [1]
The Swi3-like proteins sequences of Arabidopsis, rice, yeast and human were used as queries to search against the SGN annotation database with the BLAST program
We found that the expression of SlSWI3A and SlSWI3B is induced by cold treatment, while SlSWI3C is strongly repressed by ABA, salt and SA treatment (Figure 3B)

Summary

Introduction

The fundamental unit of chromatin is the nucleosome, which is composed of two turns of DNA wrapped around a histone octamer (two H2A-H2B dimers and one H3-H4 tetramer) [1]. The modification of chromatin can occur through multiple mechanisms, including nucleosome composition and positioning by ATP-dependent chromatin-remodeling complexes (CRCs) and enzyme complexes that modify DNA or chromatin proteins [2,3]. CRCs use energy from ATP hydrolysis [4] and change local chromatin structure, enriching accessibility of transcription factors and availability of genomic information [5]. Biochemical analysis indicated that yeast SWI/SNF CRC is composed of 12 subunits [8], and the core complex including SWI2/SNF2-type ATPase, one SNF5, and two copies of SWI3 subunits, is sufficient for execution of nucleosome remodeling in vitro [9]. Several accessory subunits associating with the core complex act as an interface for interactions with other auxiliary proteins that affect chromatin remodeling activity [10]

Methods

Results

Conclusion