Late Embryogenesis Abundant (LEA) proteins, a group of hydrophilic proteins, have been linked to survival in plants and animals in periods of stress, putatively through safeguarding enzymatic function and prevention o...Late Embryogenesis Abundant (LEA) proteins, a group of hydrophilic proteins, have been linked to survival in plants and animals in periods of stress, putatively through safeguarding enzymatic function and prevention of aggregation in times of dehydration/heat. Yet despite decades of effort, the molecular-level mechanisms defining this protective function remain unknown. In this paper, we summarize and review research discoveries of the classification of the LEA protein groups based on their amino acid sequence similarity and on the presence of distinctive conserved motifs. Moreover, we focus on high correlation between their accumulation and water deficit, reinforcing their functional relevance under abiotic stresses. We also discuss the biochemical properties of LEA proteins arising from their hydrophilic nature and by amino acid composition. Although significant similarities have not been found between the members of the different groups, a unifying and outstanding feature of most of them is their high hydrophilicity and high content of glycine. Therefore, we have highlighted the biotechnological applications of LEA genes, and the effects of over-expressing LEA genes from all LEA groups from different species of origin into different plant hosts. Apart from agronomical purposes, LEA proteins could be useful for other biotechnological applications in relation to their capacity to prevent aggregation of proteins.展开更多
The chaperone-like huntingtin-interacting protein, HYPK, has unusual biophysical behavior like an intrinsically unstructured protein (IUP). The protein exists as a (pre-) molten globule with ~37% residual structure an...The chaperone-like huntingtin-interacting protein, HYPK, has unusual biophysical behavior like an intrinsically unstructured protein (IUP). The protein exists as a (pre-) molten globule with ~37% residual structure and shows com- paction in presence of Ca++. HYPK contains no intrinsic fluorophore other than a single tyrosine and displays an anomalous fluorescence peak at around 340 nm. The anomalous peak is re- duced to 303 nm by the addition of guanidine hydrochloride and at low pH, concomitant with the emission spectrum of L-tyrosine. At high pH the peak is shifted to ~350 nm with a reduction in intensity. In presence of sodium perchlorate there is no shift in HYPK fluorescence emission peak from ~340 nm suggesting localization of the lone tyrosine residue in helical regions. In CD experiments, however, a shift in local secondary structure is noticed upon perchlorate treatment. Acrylamide quenching experiments at different Ca++ concentrations demonstrate that Ca++ does not alter the accessibility of the tyro- sine to acrylamide. In the absence of any tryp- tophan contamination, these observations vali- date that, in vitro, HYPK possesses a loosely associated (pre-) molten globule like conforma- tion with the lone tyrosine being situated within an α-helix.展开更多
基金supported jointly by grants from the Ministry of Higher Education and Scientific Research,Tunisia and the Agence Espagnole de cooperation Internationale(AECI)Officina Tecnica de Cooperacion,Spain
文摘Late Embryogenesis Abundant (LEA) proteins, a group of hydrophilic proteins, have been linked to survival in plants and animals in periods of stress, putatively through safeguarding enzymatic function and prevention of aggregation in times of dehydration/heat. Yet despite decades of effort, the molecular-level mechanisms defining this protective function remain unknown. In this paper, we summarize and review research discoveries of the classification of the LEA protein groups based on their amino acid sequence similarity and on the presence of distinctive conserved motifs. Moreover, we focus on high correlation between their accumulation and water deficit, reinforcing their functional relevance under abiotic stresses. We also discuss the biochemical properties of LEA proteins arising from their hydrophilic nature and by amino acid composition. Although significant similarities have not been found between the members of the different groups, a unifying and outstanding feature of most of them is their high hydrophilicity and high content of glycine. Therefore, we have highlighted the biotechnological applications of LEA genes, and the effects of over-expressing LEA genes from all LEA groups from different species of origin into different plant hosts. Apart from agronomical purposes, LEA proteins could be useful for other biotechnological applications in relation to their capacity to prevent aggregation of proteins.
文摘The chaperone-like huntingtin-interacting protein, HYPK, has unusual biophysical behavior like an intrinsically unstructured protein (IUP). The protein exists as a (pre-) molten globule with ~37% residual structure and shows com- paction in presence of Ca++. HYPK contains no intrinsic fluorophore other than a single tyrosine and displays an anomalous fluorescence peak at around 340 nm. The anomalous peak is re- duced to 303 nm by the addition of guanidine hydrochloride and at low pH, concomitant with the emission spectrum of L-tyrosine. At high pH the peak is shifted to ~350 nm with a reduction in intensity. In presence of sodium perchlorate there is no shift in HYPK fluorescence emission peak from ~340 nm suggesting localization of the lone tyrosine residue in helical regions. In CD experiments, however, a shift in local secondary structure is noticed upon perchlorate treatment. Acrylamide quenching experiments at different Ca++ concentrations demonstrate that Ca++ does not alter the accessibility of the tyro- sine to acrylamide. In the absence of any tryp- tophan contamination, these observations vali- date that, in vitro, HYPK possesses a loosely associated (pre-) molten globule like conforma- tion with the lone tyrosine being situated within an α-helix.
