Effect of spastic paraplegia mutations in KIF5A kinesin on transport activity
Effect of spastic paraplegia mutations in KIF5A kinesin on transport activity
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DOI：
10.1093/hmg/ddn014
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发表时间：
2008-05-01
影响因子：
3.5
通讯作者：
Woehlke, Guenther
中科院分区：
文献类型：
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作者：
Ebbing, Bettina;Mann, Klaudiusz;Woehlke, Guenther
遗传性痉挛截瘫(HSP)是由运动神经元变性引起的一种神经退行性疾病。它与至少30个基因座相关联，其中包括SPG10，它导致显性形式，起源于神经元激动素-1基因(KIF5A)的点突变。在这里，我们研究了KIF5A和四个HSP突变体的运动能力。所有突变都是单一的氨基酸交换，位于动蛋白的运动区或颈区。颈部(A361V)突变不改变微管的体外滑行特性，其他突变则降低微管亲和力或滑行速度或两者兼而有之。在激光捕获分析中，没有一个突变体沿着微管移动超过几步。用同源二聚体野生型、同源二聚体突变型和异二聚体野生型/突变型马达的混合动力分析表明，只有一个突变体(N256S)按杂合子患者的比例降低了滑行速度，而其他突变体(K253N，R280C)则没有。N256S突变体作为人造货物附着在量子点上，产生的货物种群速度较慢，运输滞后，而与其他突变体的混合物导致量子点种群很少与微管结合。这些差异表明SPG10的显性遗传是由两种不同的机制引起的，这两种机制都减少了总的货物流量，导致突触供应不足。
Hereditary spastic paraplegia (HSP) is a neurodegenerative disease caused by motoneuron degeneration. It is linked to at least 30 loci, among them SPG10, which causes dominant forms and originates in point mutations in the neuronal Kinesin-1 gene (KIF5A). Here, we investigate the motility of KIF5A and four HSP mutants. All mutations are single amino-acid exchanges and located in kinesin's motor or neck domain. The mutation in the neck (A361V) did not change the gliding properties in vitro, the others either reduced microtubule affinity or gliding velocity or both. In laser-trapping assays, none of the mutants moved more than a few steps along microtubules. Motility assays with mixtures of homodimeric wild-type, homodimeric mutant and heterodimeric wild-type/mutant motors revealed that only one mutant (N256S) reduces the gliding velocity at ratios present in heterozygous patients, whereas the others (K253N, R280C) do not. Attached to quantum dots as artificial cargo, mixtures involving N256S mutants produced slower cargo populations lagging behind in transport, whereas mixtures with the other mutants led to populations of quantum dots that rarely bound to microtubules. These differences indicate that the dominant inheritance of SPG10 is caused by two different mechanisms that both reduce the gross cargo flux, leading to deficient supply of the synapse.