Hierarchy of Lens Proteins Requiring Protection Against Heat-Induced Precipitation by the α Crystallin Chaperone

Velasco, Pauline T.; Lukas, Thomas J.; Murthy, S. N. Prasanna; Duglas-Tabor, Yvonne; Garland, Donita; Lóránd, L.

doi:10.1006/exer.1997.0358

Cited by 24 publications

(12 citation statements)

References 28 publications

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“…The major substrates of aA and aB in the lens fibre cell are k-and bcrystallin [21], although interactions with 'house-keeping' enzymes such as enolase [70], cytoskeletal elements [71] and membrane-associated proteins also occur [72,73]. It appears that the quaternary structure of the protein with a hydrophilic exterior and a hydrophobic interior, is vital to chaperone activity, as it has been observed that the structure is conserved [74] and resistant to changes in the amino acid sequence [61].…”

Section: The Crystallinsmentioning

confidence: 99%

Regulation of αA- and αB-crystallins via phosphorylation in cellular homeostasis

Thornell

Aquilina

2015

Cell. Mol. Life Sci.

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αA-Crystallin (αA) and αB-crystallin (αB) are small heat shock proteins responsible for the maintenance of transparency in the lens. In non-lenticular tissues, αB is involved in both maintenance of the cytoskeleton and suppression of neurodegeneration amongst other roles. Despite their importance in maintaining cellular health, modifications and mutations to αA and αB appear to play a role in disease states such as cataract and myopathies. The list of modifications that have been reported is extensive and include oxidation, disulphide bond formation, C- and N-terminal truncation, acetylation, carboxymethylation, carboxyethylation, carbamylation, deamidation, phosphorylation and methylation. Such modifications, notably phosphorylation, are alleged to cause changes to chaperone activity by inducing substructural changes and altering subunit exchange dynamics. Although the effect modification has on the activities of αA and αB is contentious, it has been proposed that these changes are responsible for the induction of hyperactivity and are thereby indirectly responsible for protein deposition characteristic of many diseases associated with αA and αB. This review compiles all reported sites of αA and αB modifications, and investigates the role phosphorylation, in particular, plays in cellular processes.

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Section: The Crystallinsmentioning

confidence: 99%

Regulation of αA- and αB-crystallins via phosphorylation in cellular homeostasis

Thornell

Aquilina

2015

Cell. Mol. Life Sci.

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“…aB-Crystallin prevents thermal-induced (i.e. 55 C) aggregation of lens proteins, particularly GAPDH [39]. The authors propose that the susceptible lens proteins, such as GAPDH, while in minor amounts relative to the crystallins, may contribute to initiating opacification that may consequently lead to cataracts.…”

Section: Folding Accessory Proteinsmentioning

confidence: 99%

Dynamic Oligomeric Properties

Seidler

2012

GAPDH: Biological Properties and Diversity

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This chapter provides a foundation for further research into the relationship between dynamic oligomeric properties and functional diversity. The structural basis that underlies the conformational sub-states of the GAPDH oligomer is discussed. The issue of protein stability is given a thorough analysis, since it is well-established that the primary strategy for protein oligomerization is to stabilize conformation. Several factors that affect oligomerization are described, including chemical modification by synthetic reagents. The effects of native substrates and coenzymes are also discussed. The curious feature of chloride ions having a de-stabilizing effect on native GAPDH structure is described. Additionally, the role of adenine dinucleotides in tetramer-dimer equilibrium dynamics is suggested to be a major part of the physiological regulation of GAPDH structure and function. This chapter also contends that a vast amount of useful information can come from comparative analyses of diverse species, particularly regarding protein stability and subunit-subunit interaction. Lastly, the concept of domain exchange is introduced as a means of understanding the stabilization of dynamic oligomers, suggesting that inter-subunit contacts may also be a way of masking docking sites to other proteins.

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“…Metalloaminopeptidases (mAPs) are key players in many biological processes, including cellular targeting of proteins [1, 2], protein degradation [1, 3, 4], aging [5-10], tissue repair [11-15], cataract formation [16-22], HIV infectivity [23-26], angiogenesis [27-31], and carcinogenesis [27, 32-34]. A biomedically important family of mAPs is that of the dinuclear mAPs, also known as “cocatalytic” mAPs [35].…”

Section: Introductory Statementmentioning

confidence: 99%

Heterologous expression and purification of Vibrio proteolyticus (Aeromonas proteolytica) aminopeptidase: A rapid protocol

Hartley

Bennett

2009

Protein Expression and Purification

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Metalloaminopeptidases (mAPs) are enzymes that are involved in HIV infectivity, tumor growth and metastasis, angiogenesis, and bacterial infection. Investigation of structure-function relationships in mAPs is a prerequisite to rational design of anti-mAP chemotherapeutics. The most intensively studied member of the biomedically important dinuclear mAPs is the prototypical secreted Vibrio proteolyticus di-zinc aminopeptidase (VpAP). The wild-type enzyme is readily purified from the supernatant of cultures of V. proteolyticus, but recombinant variants require expression in Escherichia coli. A greatly improved system for the purification of recombinant VpAP is described. A VpAP-(His)6 polypeptide, containing an N-terminal propeptide, and a C-terminal (His)6 adduct, was purified by metal ion affinity chromatography from the supernatant of cultures of E. coli. This single step replaced the sequence of (NH4)2SO4 fractionation, and anion exchange and hydrophobic interaction chromatographic separations of earlier methods. Traditionally, recombinant VpAP proenzyme has been treated with proteinase K and with heat (70 °C), to remove the N- and C-terminal regions, and yield the mature active enzyme. This method is unsuitable for VpAP variants that are unstable towards these treatments. In the new method, the hitherto noted, but not fully appreciated, ability of VpAP to autocatalyze the hydrolysis of the N-terminal propeptide and C-terminal regions was exploited; extensive dialysis of the highly purified VpAP-(His)6 full-length polypeptide yielded the mature active protein without recourse to proteinase K or heat treatment. Purification of variants that have previously defied isolation as mature forms of the protein was thus carried out.

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Hierarchy of Lens Proteins Requiring Protection Against Heat-Induced Precipitation by the α Crystallin Chaperone

Cited by 24 publications

References 28 publications

Regulation of αA- and αB-crystallins via phosphorylation in cellular homeostasis

Regulation of αA- and αB-crystallins via phosphorylation in cellular homeostasis

Dynamic Oligomeric Properties

Heterologous expression and purification of Vibrio proteolyticus (Aeromonas proteolytica) aminopeptidase: A rapid protocol

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