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首页> 外文期刊>RSC Advances >N- and C-terminal regions of the small heat shock protein IbpA from Acholeplasma laidlawii competitively govern its oligomerization pattern and chaperone-like activity
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N- and C-terminal regions of the small heat shock protein IbpA from Acholeplasma laidlawii competitively govern its oligomerization pattern and chaperone-like activity

机译：来自Acholeplasma Laidlawii的小型热休克蛋白IBPA的N-和C末端区域竞争地区控制其寡聚化模式和伴侣样活动

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摘要

Small heat shock proteins (sHSPs) are ubiquitous molecular chaperones preventing the irreversible denaturation of proteins. While in Escherichia coli two sHSPs IbpA and IbpB work in strong cooperation, the sole Mollicute with free-living ability Acholeplasma laidlawii carries a single gene encoding the sHSP protein Al IbpA. In vitro , independently of the temperature, Al IbpA forms a heterogeneous mixture of approximately 24-mer globules, fibrils and huge protein aggregates. The removal of either 12 or 25 N-terminal amino acids led to the formation of fibrils and enhanced the protein ability to prevent the temperature-induced aggregation of insulin, assuming the fibrillar form as an active protein. In turn, the deletion of the C-terminus or substitution of C-terminal LEL motif by SEP decreased the temperature stability of Al IbpA and eliminated its chaperone function completely, although the protein remained predominantly in a globular state. This suggests that the C-terminal LEL motif is necessary for the chaperon-like activity of Al IbpA and fibril formation. Double N- and C-terminal truncations abolished both the chaperone-like activity and huge oligomer formation. Since the globular form of sHSPs is considered as their inactive form, our data suggest that the N-terminus of Al IbpA is responsible for the huge globule (low-active form) formation and behaves as an intramolecular inhibitor of the fibrils (active form) formation and substrates binding. Taken together these data demonstrate non-trivial properties of Al IbpA, in which the competitive action of N- and C-termini governs the equilibrium between either fibrillar or globular structures representing a possible molecular mechanism of the Al IbpA activity regulation.
机译：小型热休克蛋白（SHSP）是普遍存在的分子伴侣，防止蛋白质不可逆的变性。虽然在大肠杆菌两次SHSPS IBPA和IBPB工作中强有力的合作中，但唯一的髓质术与自由生活能力Acholeplasma Laidlawii携带一种编码Shsp蛋白AL IBPA的单一基因。体外，独立于温度，Al IBPa形成约24-MEL球，原纤维和巨大的蛋白质聚集体的异质混合物。去除12或25个N-末端氨基酸导致原纤维的形成，并提高了防止胰岛素的温度诱导的胰岛素聚集的蛋白质能力，假设纤维状形成为活性蛋白。反过来，通过SEP删除C末端或替代C末端LEL基序，降低了Al IBPA的温度稳定性，并完全消除了其伴侣功能，尽管蛋白质留在球状状态。这表明C末端LEL基序是Al IBPA和原纤维形成的伴侣状活性所必需的。废除了双N和C末端截短，废除了伴侣样活性和巨大的低聚物形成。由于SHSP的球状形式被认为是它们的非活动形式，因此我们的数据表明Al IBPA的N-末端对巨大的球状（低活性形式）形成并表现为原纤维的分子内抑制剂（活性形式）形成和基材结合。将这些数据展示了Al IBPA的非琐碎性质，其中N-和C-Termini的竞争作用管辖代表Al IBPA活性调节的可能分子机制的纤维结或球状结构之间的均衡。

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