Identification and in silico analysis of the Citrus HSP70 molecular chaperone gene family

Abstract

The completion of the genome sequencing of the Arabidopsis thaliana model system provided a powerful molecular tool for comparative analysis of gene families present in the genome of economically relevant plant species. In this investigation, we used the sequences of the Arabidopsis Hsp70 gene family to identify and annotate the Citrus Hsp70 genes represented in the CitEST database. Based on sequence comparison analysis, we identified 18 clusters that were further divided into 5 subgroups encoding four mitochondrial mtHsp70s, three plastid csHsp70s, one ER luminal Hsp70 BiP, two HSP110/SSE-related proteins and eight cytosolic Hsp/Hsc70s. We also analyzed the expression profile by digital Northern of each Hsp70 transcript in different organs and in response to stress conditions. The EST database revealed a distinct population distribution of Hsp70 ESTs among isoforms and across the organs surveyed. The Hsp70-5 isoform was highly expressed in seeds, whereas BiP, mitochondrial and plastid HSp70 mRNAs displayed a similar expression profile in the organs analyzed, and were predominantly represented in flowers. Distinct Hsp70 mRNAs were also differentially expressed during Xylella infection and Citrus tristeza viral infection as well as during water deficit. This in silico study sets the groundwork for future investigations to fully characterize functionally the Citrus Hsp70 family and underscores the relevance of Hsp70s in response to abiotic and biotic stresses in Citrus.

Roles of Hsp70s in Stress Responses of Microorganisms, Plants, and Animals

“…In Citrus , the ER-resident Hsp70-5 shows seed-specific expression and has a key function in seed desiccation tolerance. Furthermore, Citrus Hsp70-5 is highly expressed in response to biotic stresses, such as Xylella infection and Citrus tristeza viral infection, due to activation of the UPR signaling pathway [ 37 ].…”

Inhibition of JAK2/STAT3 Signaling Pathway Suppresses Proliferation of Burkitt’s Lymphoma Raji Cells via Cell Cycle Progression, Apoptosis, and Oxidative Stress by Modulating HSP70

“…Among them, HSP70, which functions as a molecular chaperone, is one of the most abundant and best-characterized HSPs [ 10 ]. Under adverse environmental conditions, the stress-induced members of the Hsp70 family are reported to be involved in the re-folding and degradation of misfolded proteins [ 11 ]. Recently, accumulating evidence has revealed that HSP70 is abnormally over-expressed in many cancers, such as bladder cancer [ 12 ], colon cancer [ 13 ], and breast cancer [ 14 ], to compensate for the basal stress due to nutrient shortage, growth dysregulation and unfolded protein accumulation [ 15 ].…”

Biosíntesis de Carotenoides durante la Conservación Postcosecha de Frutos Citricos

“…En este trabajo la acumulación de lectinas en el flavedo de la naranja 'Navelina' parece que estuvo más relacionada con la adaptación al frío durante la conservación a 2 ºC, dado que incrementó su acumulación a lo largo del periodo de almacenamiento, al igual que se ha descrito en otros vegetales como en el trigo (Timofeeva et al, 2000;Timofeeva et al, 2008) o en el arroz (Komatsu et al, 2009), donde la adaptación al frío estuvo acompañada de un aumento de lectinas (Garaeva et al, 2006). Por otro lado, la HSP 70 pertenece a una familia de proteínas relacionadas con el estrés (Fietto et al, 2007), que presentan actividad chaperona y confieren termotolerancia (Iba, 2002;Kotak et al, 2007). También se indujeron a bajas temperaturas dos HSP de bajo peso molecular (sHSP) (Tabla 9), aunque en menor medida que las HSP 70.…”