The Structural Biology of Bcl-xL

Interactions between the pro-survival and pro-apoptotic members of the Bcl-2 family of proteins dictate whether a cell lives or dies. Much of our knowledge of the molecular details of these interactions has come from biochemical and structural studies on the pro-survival protein Bcl-xL. The first high-resolution structure of any Bcl-2 family member was of Bcl-xL, which revealed the conserved topology amongst all family members. Subsequent structures of Bcl-xL complexes with pro-apoptotic ligands demonstrated the general features of all pro-survival:pro-apoptotic complexes. Structural studies involving Bcl-xL were also the basis for the discovery of the first small-molecule pro-survival protein inhibitors, leading ultimately to the development of a new class of drugs now successfully used for cancer treatment in the clinic. This article will review our current knowledge of the structural biology of Bcl-xL and how this has impacted our understanding of the molecular details of the intrinsic apoptotic pathway.

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Rapid high-resolution structure analysis of small, biotechnologically relevant enzymes by cryo-electron microscopy

10.1101/2021.06.15.448552 ◽

2021 ◽

Author(s):

Nicole Dimos ◽

Carl P.O. Helmer ◽

Andrea M. Chanique ◽

Markus C. Wahl ◽

Robert Kourist ◽

...

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Structural Biology ◽

Structure Analysis ◽

Cryo Electron Microscopy ◽

High Resolution Structure ◽

Fast Development ◽

Pharmaceutical Industries ◽

Exquisite Specificity ◽

Resolution Structure

Enzyme catalysis has emerged as a key technology for developing efficient, sustainable processes in the chemical, biotechnological and pharmaceutical industries. Plants provide large and diverse pools of biosynthetic enzymes that facilitate complex reactions, such as the formation of intricate terpene carbon skeletons, with exquisite specificity. High-resolution structural analysis of these enzymes is crucial to understand their mechanisms and modulate their properties by targeted engineering. Although cryo-electron microscopy (cryo-EM) has revolutionized structural biology, its applicability to high-resolution structure analysis of comparatively small enzymes is so far largely unexplored. Here, we show that cryo-EM can reveal the structures of ~120 kDa plant borneol dehydrogenases at or below 2 Å resolution, paving the way for the fast development of new biocatalysts that provide access to bioactive terpenes and terpenoids.

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Detergent-free systems for structural studies of membrane proteins

Biochemical Society Transactions ◽

10.1042/bst20201080 ◽

2021 ◽

Author(s):

Youzhong Guo

Keyword(s):

High Resolution ◽

Membrane Proteins ◽

Cell Membrane ◽

Membrane Protein ◽

Structural Biology ◽

Membrane Lipids ◽

Native Cell ◽

Lipid Particles ◽

High Resolution Structure ◽

Resolution Structure

Membrane proteins play vital roles in living organisms, serving as targets for most currently prescribed drugs. Membrane protein structural biology aims to provide accurate structural information to understand their mechanisms of action. The advance of membrane protein structural biology has primarily relied on detergent-based methods over the past several decades. However, detergent-based approaches have significant drawbacks because detergents often damage the native protein–lipid interactions, which are often crucial for maintaining the natural structure and function of membrane proteins. Detergent-free methods recently have emerged as alternatives with a great promise, e.g. for high-resolution structure determinations of membrane proteins in their native cell membrane lipid environments. This minireview critically examines the current status of detergent-free methods by a comparative analysis of five groups of membrane protein structures determined using detergent-free and detergent-based methods. This analysis reveals that current detergent-free systems, such as the styrene-maleic acid lipid particles (SMALP), the diisobutyl maleic acid lipid particles (DIBMALP), and the cycloalkane-modified amphiphile polymer (CyclAPol) technologies are not better than detergent-based approaches in terms of maintenance of native cell membrane lipids on the transmembrane domain and high-resolution structure determination. However, another detergent-free technology, the native cell membrane nanoparticles (NCMN) system, demonstrated improved maintenance of native cell membrane lipids with the studied membrane proteins, and produced particles that were suitable for high-resolution structural analysis. The ongoing development of new membrane-active polymers and their optimization will facilitate the maturation of these new detergent-free systems.

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High resolution structure of a partially folded insulin aggregation intermediate

10.1101/716845 ◽

2019 ◽

Author(s):

Bhisma N Ratha ◽

Rajiv K Kar ◽

Jeffrey R Brender ◽

Bankanidhi Sahoo ◽

Sujan Kalita ◽

...

Keyword(s):

High Resolution ◽

Structural Biology ◽

Nucleation Site ◽

Oligomer Formation ◽

High Resolution Structure ◽

Partially Folded Intermediate ◽

Monomeric Structure ◽

A Chain ◽

Receptor Interface ◽

Resolution Structure

AbstractInsulin has long served as a model for protein aggregation, both because of the importance of aggregation in insulin manufacture and because the structural biology of insulin has been extensively characterized. Despite intensive study, details about the initial triggers for aggregation have remained elusive at the molecular level. We show here that at acidic pH, the aggregation of insulin is likely initiated by a partially folded monomeric intermediate whose concentration is controlled by an off-pathway micellar species. High resolution structures of the partially folded intermediate show that it is coarsely similar to the initial monomeric structure but differs in subtle details – the A chain helices on the receptor interface are more disordered and the B chain helix moves away from C-terminal A chain helix. The result of these movements is the creation of a hydrophobic cavity in the center of the protein that may serve as nucleation site for oligomer formation. Knowledge of this transition may aid in the engineering of insulin variants that retain the favorable pharamacokinetic properties of monomeric insulin but are more resistant to aggregation.

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