Heat Treatment of Small Heat Shock Proteins α-Crystallin and Hsp16.3: Structural Changes vs. Chaperone-like Activity

Both α crystallin from bovine eye lens and Hsp16.3 from Mycobacterium tuberculosis are members of the small heat shock protein family. They were preincubated at 100 ℃ for 15 min and then cooled on ice immediately. The chaperone like activities of preheated proteins were measured at 37 ℃ using DTT treated insulin B chains as substrates. Both preheated proteins exhibited greatly enhanced chaperone like activities, accompanied with almost unchanged secondary structures and surface hydrophobicity but with a minor change in tertiary structures. The dramatically enhanced chaperone like activities of preheated α crystallin and Hsp16.3 may have resulted from the irreversible change in the tertiary structure as detected by near UV CD spectra.

Expression analysis of two reverse duplicated small heat shock protein genes in rice(Oryza sativa L.)

supported by grants from the National Natural Science Foundation of China （30671178）;the Shanxi Province Science Foundation for Youths, China （2014021029-2）

Bioinformatic analysis of embryo development related small heat shock protein Hsp26 in Artemia species

Artemia embryos can endure extreme temperature, long-term anoxia, desiccation and other wide variety of stressful conditions. How the embryos survive these stresses is a very interesting and unsolved subject. To solve this question we analyzed the nucleotide and deduced protein sequence for Hsp26, a molecular chaperone specific to Artemia embryo development, cDNAs of Hsp26 were sequenced from eight Artemia species and deduced Hsp26 amino acid sequences were analyzed. Computer-assisted analysis indicated that the 5＇-untranslated region and all the 3 introns contain many putative cis-acting elements for Hsp26 gene expression during development, including heat shock elements （HSEs）, Dfd, dl, CF2-II, Hb and AP-1 binding sites. Secondary structure of the Hsp26 3＇-untranslated terminator contains the basic structure basis for transcriptional termination. Hsp26 shares sequence similarity with sHSPs （small heat shock protein） from other organisms. The physico-chemical properties of the deduced protein, such as theoretical molecular weight, protein extinction coefficient, isoelectric point and antigenic sites were also obtained. One seven-peptide nuclear localization signals （NLS） ＂PFRRRMM＂ was found, which suggested that the Hsp26 protein was hypothesized to be located inside the nucleus. The numbers of phosphorylation sites of serine, threonine and tyrosine and kinase specific phosphorylation sites are also located in Hsp26 protein sequence. These studies will help us achieve a better understanding of Hsp26 and broad implications for sHSPs function in crustacean embryo development.

Cloning and Drought Resistance Analysis of Soybean GmHsps_p23-like Gene

Soybean(Glycine max(L.)Merr.)is an important cultivated crop,which requires much water during its growth,and drought seriously affects soybean yields.Studies have shown that the expression of small heat shock proteins can enhance drought resistance,cold resistance and salt resistance of plants.In this experiment,soybean GmHsps_p23-like gene was successfully cloned by RT-PCR,the protein encoded by the GmHsps_p23-like gene was subjected to bioinformatics analysis,and the pCAMBIA3301-GmHsps_p23-like overexpression vector and pCBSG015-GmHsps_p23-like gene editing vector were constructed.Agrobacterium-mediated method was used to transform soybeans to obtain positive plants.RT-PCR detection,rehydration experiment and drought resistance physiological and biochemical index detection were performed on the T2 generation positive transgenic soybean plants identified by PCR and Southern hybridization.The results showed that the overexpression vector plant GmHsps_p23-like gene expression increased.After rehydration,the transgenic overexpression plants returned to normal growth,and the damage to the plants was low.After drought stress,the SOD and POD activities and the PRO content of the transgenic overexpression plants increased,while the MDA content decreased.The reverse was true for soybean plants with genetically modified editing vectors.The drought resistance of the overexpressed soybeans under drought stress was higher than that of the control group,and had a stronger drought resistance.It showed that the expression of soybean GmHsps_p23-like gene can improve the drought resistance of soybean.The cloning and functional verification of soybean GmHsps_p23-like gene had not been reported yet.This is the first time that PCR technology has been used to amplify the soybean GmHsps_p23-like gene and construct an expression vector for this gene.This research has laid the foundation for transgenic technology to improve plant drought resistance and cultivate new drought-resistant transgenic soybean varieties.

Plasma membrane-localized Hsp40/DNAJ chaperone protein facilitates OsSUVH7-OsBAG4-OsMYB106 transcriptional complex formation for Os HKT1;5 activation

The salinization of irrigated land affects agricultural productivity.HIGH-AFFINITY POTASSIUM(K+)TRANSPORTER 1;5(OsHKT1;5)-dependent sodium(Na+)transport is a key salt tolerance mechanism during rice growth and development.Using a previously generated high-throughput activation tagging-based T-DNA insertion mutant pool,we isolated a mutant exhibiting salt stress-sensitive phenotype,caused by a reduction in OsHKT1;5transcripts.The salt stress-sensitive phenotype of this mutant results from the loss of function of OsDNAJ15,which encodes plasma membranelocalized heat shock protein 40(Hsp40).osdnaj15loss-of-function mutants show decreased plant height,increased leaf angle,and reduced grain number caused by shorter panicle length and fewer branches.On the other háand,OsDNAJ15-overexpression plants showed salt stress-tolerant phenotypes.Intriguingly,salt stress facilitates the nuclear relocation of OsDNAJ15 so that it can interact with OsBAG4,and OsDNAJ15 and OsBAG4synergistically facilitate the DNA-binding activity of OsMYB106 to positively regulate the expression of OsHKT1;5.Overall,our results reveal a novel function of plasma membrane-localized Hsp40protein in modulating,alongside chaperon regulator OsBAG4,transcriptional regulation under salinity stress tolerance.