Structural features underlying recognition and translocation of extracellular polysaccharides

Zimmer, Jochen

doi:10.1098/rsfs.2018.0060

Cited by 12 publications

(7 citation statements)

References 75 publications

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“…We argue these structures were published with insufficient supporting evidence to justify the very high level of the publications, with their implicit authority, particularly given the uncertainty around the mechanistic interpretation of structural features. Perhaps more tellingly, however, these structures have been presented and discussed in a number subsequent reviews [1,[42][43][44][45][46][47][48][49], essentially without reservation regarding their veracity, or caveats around the requirement for further independent support. We believe that all of this indicates a general level of certitude that the structures are unlikely to be incorrect, that is not warranted.…”

Section: Resultsmentioning

confidence: 99%

Is the emperor wearing shorts? The published structures of ABC transporters

Jones

George

2020

FEBS Letters

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ABC transporters use the energy of ATP binding and hydrolysis to transport substrates across cellular membranes. They comprise two highly conserved nucleotide binding domains and two transmembrane domains that form the transmembrane channel and contain the substrate binding sites. Structural analyses have found a variety of seemingly unrelated folds for the ABC transporter transmembrane domains, and from these, a set of diverse mechanistic models has been inferred. Nevertheless, in spite of the explosion in structure determination of ABC transporters in the last decade, advancement in certainty and clarity as to fundamental aspects of their molecular mechanisms remains elusive. With this in mind, here we put and examine the question: Could current ABC structures differ from the physiologic membrane-embedded forms?

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Section: Resultsmentioning

confidence: 99%

Is the emperor wearing shorts? The published structures of ABC transporters

Jones

George

2020

FEBS Letters

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“…Translocation of the acceptor is carried out by three conserved features: a QxxRW motif, a finger helix with a TED motif, and a gating loop. The conserved QxxRW sequence is located near the channel’s entrance and is responsible for the stabilization of the acceptor through π and hydrogen bonds ( Morgan et al, 2016 ; Zimmer, 2019 ). Additionally, the finger helix’s TED motif interacts with the acceptor polysaccharide by forming hydrogen bonds with three hydroxyls of terminal Glc.…”

Section: Proteins Involved In Xyloglucan Biosynthesismentioning

confidence: 99%

Xyloglucan Biosynthesis: From Genes to Proteins and Their Functions

Julian

Zabotina²

2022

Front. Plant Sci.

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The plant’s recalcitrant cell wall is composed of numerous polysaccharides, including cellulose, hemicellulose, and pectin. The most abundant hemicellulose in dicot cell walls is xyloglucan, which consists of a β-(1- > 4) glucan backbone with α-(1- > 6) xylosylation producing an XXGG or XXXG pattern. Xylose residues of xyloglucan are branched further with different patterns of arabinose, fucose, galactose, and acetylation that varies between species. Although xyloglucan research in other species lag behind Arabidopsis thaliana, significant advances have been made into the agriculturally relevant species Oryza sativa and Solanum lycopersicum, which can be considered model organisms for XXGG type xyloglucan. In this review, we will present what is currently known about xyloglucan biosynthesis in A. thaliana, O. sativa, and S. lycopersicum and discuss the recent advances in the characterization of the glycosyltransferases involved in this complex process and their organization in the Golgi.

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“…6b). Notably, this motif is rich in acidic/aromatic residues that are capable of forming H-bonds/"greasy slides" frequently found in protein-sugar interactions 44 .…”

Section: Identification Of the Gpi-binding Sitementioning

confidence: 99%

Molecular insights into biogenesis of glycosylphosphatidylinositol anchor proteins

Jia

et al. 2022

Preprint

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Eukaryotic cells are coated with an abundance of glycosylphosphatidylinositol anchor proteins (GPI-APs) that play crucial roles in fertilization, neurogenesis, and immunity. Covalent addition of structurally diverse GPI anchorages at the carboxyl termini of target proteins is catalyzed by an endoplasmic reticulum integral membrane GPI transamidase complex (GPI-T) conserved among all eukaryotes. Despite its important role in developmental and cancer biology, a detailed picture of this intricate multi-component machinery remains elusive. Here, we report the cryo-electron microscopy (EM) structure of the human GPI-T complex at a global 2.53 Å resolution, revealing an assembly mechanism whereby the catalytic subunit PIGK is optimally positioned to accommodate its characteristic amphipathic substrates. Further, structural and functional characterizations suggest a previously unrecognized composite GPI-binding site formed by PIGU/PIGK/PIGT subunits and rationalize genetic diseases associated with GPI-T point mutations. Our work presents an important step towards the mechanistic understanding of GPI-AP biosynthesis.

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Structural features underlying recognition and translocation of extracellular polysaccharides

Cited by 12 publications

References 75 publications

Is the emperor wearing shorts? The published structures of ABC transporters

Is the emperor wearing shorts? The published structures of ABC transporters

Xyloglucan Biosynthesis: From Genes to Proteins and Their Functions

Molecular insights into biogenesis of glycosylphosphatidylinositol anchor proteins

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