Hsp70 chaperones assist in protein folding, disaggregation, and membrane translocation by binding to substrate proteins with an ATP-regulated affinity that relies on allosteric coupling between ATP-binding and substrate-binding domains. We have studied single- and two-domain versions of the E. coli Hsp70, DnaK, to explore the mechanism of interdomain communication. We show that the interdomain linker controls ATPase activity by binding to a hydrophobic cleft between subdomains IA and IIA. Furthermore, the domains of DnaK dock only when ATP binds and behave independently when ADP is bound. Major conformational changes in both domains accompany ATP-induced docking: of particular importance, some regions of the substrate-binding domain are stabilized, while those near the substrate-binding site become destabilized. Thus, the energy of ATP binding is used to form a stable interface between the nucleotide- and substrate-binding domains, which results in destabilization of regions of the latter domain and consequent weaker substrate binding.

Zinc deficiency is a common problem leading to severe decreases in grain yield and has detrimental effects on nutritional quality in cereals. Wild emmer wheat, Triticum turgidum ssp. dicoccoides, exhibits a potential genetic resource for wheat improvement due to its compatibility with modern wheat. In this study, Zn deficiency response of wild progenitors and modern wheat were examined using molecular and physiological approaches with plants grown under various Zn concentrations. The results revealed wide variation in response to Zn deficiency between wild emmer accessions. Among the wild emmer accessions studied, accession MM 5/4 was found to be most tolerant and accession 19-36 was the most sensitive to Zn deficiency. To better understand Zn transport mechanisms in wild emmer wheat, we analyzed the expression patterns of a ZRT/IRT-like gene, Zrt-, Irt-like protein (ZIP)1, in the roots and shoots of several accessions that were maintained on different concentrations of Zn. Quantitative real-time polymerase chain reaction results revealed that ZIP1 transcript levels are elevated with decreasing Zn supply in all accessions. Particularly, ZIP1 transcript accumulation was lower in the roots of accession MM 5/4 while the susceptible, 19-36 accession, has elevated levels of ZIP1 transcript, revealing a Zn deficiency response for this genotype. We also identified and cloned a full-length ZIP1 transporter, named TdZIP1, and further analyzed the corresponding protein sequence for structural attributes. Under Zn deficiency, deleting the last 20 amino Emel Durmaz and Ceyda Coruh equally contributed to this work.Electronic supplementary material The online version of this article (

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Bentgrass (Agrostis spp.), a genus of the Poaceae family, consists of more than 200 species and is mainly used in athletic fields and golf courses. Creeping bentgrass (A. stolonifera L.) is the most commonly used species in maintaining golf courses, followed by colonial bentgrass (A. capillaris L.) and velvet bentgrass (A. canina L.). The presence and nature of sequence related amplified polymorphism (SRAP) at the cDNA level were investigated. We isolated 80 unique cDNA fragment bands from these species using 56 SRAP primer combinations. Sequence analysis of cDNA clones and analysis of putative translation products revealed that some encoded amino acid sequences were similar to proteins involved in DNA synthesis, transcription, and signal transduction. The cytosolic glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene (GenBank accession no. EB812822) was also identified from velvet bentgrass, and the corresponding protein sequence is further analyzed due to its critical role in many cellular processes. The partial peptide sequence obtained was 112 amino acids long, presenting a high degree of homology to parts of the N-terminal and C-terminal regions of cytosolic phosphorylating GAPDH (GapC). The existence of common expressed sequence tags (ESTs) revealed by a minimum evolutionary dendrogram among the Agrostis ESTs indicated the usefulness of SRAP for comparative genome analysis of transcribed genes in the grass species.

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