Structure of the Bcs1 AAA-ATPase suggests an airlock-like translocation mechanism for folded proteins

Kater, Lukas; Wagener, Nikola; Berninghausen, Otto; Becker, Thomas; Neupert, Walter; Beckmann, Roland

doi:10.1038/s41594-019-0364-1

Cited by 33 publications

(36 citation statements)

References 45 publications

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“…A recent study reported a heptameric assembly of yeast Bcs1, an AAA+ ATPase, involved in the transport of folded proteins. 69 However, Bcs1 has a domain architecture different from that of ClpL. To the best of our knowledge, this is the first case where an AAA+ ATPase is active as a heptamer-based oligomer.…”

Section: Discussionmentioning

confidence: 87%

ClpL is a functionally active tetradecameric AAA+ chaperone, distinct from hexameric/dodecameric ones

et al. 2020

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AAA+ (ATPases associated with diverse cellular activities) chaperones are involved in a plethora of cellular activities to ensure protein homeostasis. The function of AAA+ chaperones is mostly modulated by their hexameric/dodecameric quaternary structures. Here we report the structural and biochemical characterizations of a tetradecameric AAA+ chaperone, ClpL from Streptococcus pneumoniae. ClpL exists as a tetradecamer in solution in the presence of ATP. The cryo-EM structure of ClpL at 4.5 Å resolution reveals a striking tetradecameric arrangement. Solution structures of ClpL derived from small-angle X-ray scattering data suggest that the tetradecameric ClpL could assume a spiral conformation found in active hexameric/dodecameric AAA+ chaperone structures. Vertical positioning of the middle domain accounts for the head-to-head arrangement of two heptameric rings. Biochemical activity assays with site-directed mutagenesis confirmed the critical roles of residues both in the integrity of the tetradecameric arrangement and activities of ClpL. Non-conserved Q321 and R670 are crucial in the heptameric ring assembly of ClpL. These results establish that ClpL is a functionally active tetradecamer, clearly distinct from hexameric/dodecameric AAA+ chaperones.

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Section: Discussionmentioning

confidence: 87%

ClpL is a functionally active tetradecameric AAA+ chaperone, distinct from hexameric/dodecameric ones

et al. 2020

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“…A notable difference between the Apo1 and Apo2 state was found in the Bcs1-specific domain. While the pore separating the substrate-binding cavity and TM basket domain in the Apo1 form is tightly sealed, that for Apo2 appears to be open [31].…”

Section: Structure Of Apo Bcs1mentioning

confidence: 99%

“…They contact each other on the IMS side of the membrane, but on the matrix side at the beginning of the Bcs1-specific domain two neighboring helices are separated by a 25 A gap. Interestingly, two apo forms have been observed for the yBcs1 based on cryo-EM 3D classification and refinement, which were referred to as Apo1 and Apo2 [31]. A notable difference between the Apo1 and Apo2 state was found in the Bcs1-specific domain.…”

Section: Structure Of Apo Bcs1mentioning

confidence: 99%

“…Structures of the mBcs1 and yBcs1 in apo form were recently determined by Cryo-EM [30,31]. Because the structures are similar in most aspects, the following discussion will be based largely on the mBcs1.…”

Section: Structure Of Apo Bcs1mentioning

confidence: 99%

“…Despite the clear evidence of involvement of Bcs1 in Complex III assembly shown by genetic and biochemical studies, exactly how Bcs1 performs its function remains unclear. The recent reported structures of mouse (mBcs1) and yeast (yBcs1) Bcs1 shed new lights on the assembly of Complex III, mutations linked to Complex III deficiency, and the mechanism of function of a distinct family of AAA proteins [30,31].…”

Section: Introductionmentioning

confidence: 99%

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Structural snapshots of the cellular folded protein translocation machinery Bcs1

Xia

2020

The FEBS Journal

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Proteins destined to various intra-and extra-cellular locations must traverse membranes most frequently in an unfolded form. When the proteins being translocated need to remain in a folded state, specialized cellular transport machinery is used. One such machine is the membrane-bound AAA protein Bcs1 (Bcs1), which assists the iron-sulfur protein, an essential subunit of the respiratory Complex III, across the mitochondrial inner membrane. Recent structure determinations of mouse and yeast Bcs1 in three different nucleotide states reveal its homo-heptameric association and at least two dramatically different conformations. The apo and ADP-bound structures are similar, both containing a large substratebinding cavity accessible to the mitochondrial matrix space, which contracts by concerted motion of the ATPase domains upon ATP binding, suggesting that bound substrate could then be pushed across the membrane. ATP hydrolysis drives substrate release and resets Bcs1 conformation back to the apo/ADP form. These structures shed new light on the mechanism of folded protein translocation across a membrane, provide better understanding on the assembly process of the respiratory Complex III, and correlate clinical presentations of disease-associated mutations with their locations in the 3D structure.

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Modelling of BCS1L-related human mitochondrial disease in Drosophila melanogaster

et al. 2021

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Mutations in BCS1L are the most frequent cause of human mitochondrial disease linked to complex III deficiency. Different forms of BCS1L-related diseases and more than 20 pathogenic alleles have been reported to date. Clinical symptoms are highly heterogenous, and multisystem involvement is often present, with liver and brain being the most frequently affected organs. BCS1L encodes a mitochondrial AAA + -family member with essential roles in the latest steps in the biogenesis of mitochondrial respiratory chain complex III. Since Bcs1 has been investigated mostly in yeast and mammals, its function in invertebrates remains largely unknown. Here, we describe the phenotypical, biochemical and metabolic consequences of Bcs1 genetic manipulation in Drosophila melanogaster. Our data demonstrate the fundamental role of Bcs1 in complex III biogenesis in invertebrates and provide novel, reliable models for BCS1L-related human mitochondrial diseases. These models recapitulate several features of the human disorders, collectively pointing to a crucial role of Bcs1 and, in turn, of complex III, in development, organismal fitness and physiology of several tissues.

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Structure of the Bcs1 AAA-ATPase suggests an airlock-like translocation mechanism for folded proteins

Cited by 33 publications

References 45 publications

ClpL is a functionally active tetradecameric AAA+ chaperone, distinct from hexameric/dodecameric ones

ClpL is a functionally active tetradecameric AAA+ chaperone, distinct from hexameric/dodecameric ones

Structural snapshots of the cellular folded protein translocation machinery Bcs1

Modelling of BCS1L-related human mitochondrial disease in Drosophila melanogaster

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