Individual Differences Of The Small Heat Shock Protein 23 And 27 Upstream Sequence At The Nucleotide Level

Small heat shock proteins are an important class of stress proteins in organisms, participating in a variety of cellular physiological and biochemical processes, and protecting cells from several types of aggressions, such as heat shock, desiccation, and drugs, etc. The regulation of shsp gene transcription is classified into basic and inducible transcriptions.The upstream regulatory sequences are critical for transcription of the SHsp protein-encoding genes, especially the 200bp sequences upstream from the starting point. They can be divided into two categories. One is gene-specific regulatory sequences, they typically situate at specific sites with various distances upstream from the transcription starting site. These sequences can be recognized by a variety of transcriptional activators and repressers. The other category is sequences referred to as the core promoter elements, usually including TATA box, an initiator element, downstream promoter element, etc., which are recognized by TFIID.We use D.melanogaster as the experimental material, and analyze the upstream sequence variations of hsp23 and hsp27, which provides experimental evidence for the differences hi stress resistance and longevity among individuals. The relationship between these genes and their regulatory factors is analyzed. Through the alignment ofhsp23 and hspTI of individuals, we are able to investigate the locations and characteristics of the variations in the DNA sequences, the possible changes of DNA structures and the binding with the regulatory factors, and as a result, the influence on lifespan and resistance against extreme conditions.We have cloned six hsp23 and five hsp27 upstream sequences with 400bp and 389bp respectively, and find that most variations occur near the TATA box while the TATA sequence remains unchanged, which indicatesthat the TATA box is likely to play a significant role in the regulation of the gene expression, the sequence within ?0bp from the TATA box, however, is not important. What's more, most of the mutations are A to T or T to A, which suggests that these mutations will not have obvious impact on the structure of chromatin and the binding with the regulatory factors. But some changes are C to T, A to G, or T to C, which may result in larger changes of the gene regulation level.