4CXN

Crystal structure of human insulin analogue (NMe-AlaB8)-insulin crystal form I

Summary for 4CXN

• Entry DOI: 10.2210/pdb4cxn/pdb
• Related: 4CXL
• Descriptor: INSULIN A CHAIN, INSULIN B CHAIN (3 entities in total)
• Functional Keywords: hormone, diabetes
• Biological source: HOMO SAPIENS (HUMAN); More
• Cellular location: Secreted: P01308 P01308
• Total number of polymer chains: 2
• Total formula weight: 5845.70

Authors

Kosinova, L.,Veverka, V.,Novotna, P.,Collinsova, M.,Urbanova, M.,Jiracek, J.,Moody, N.R.,Turkenburg, J.P.,Brzozowski, A.M.,Zakova, L. (deposition date: 2014-04-07, release date: 2014-05-28, Last modification date: 2023-12-20)

Primary citation

Kosinova, L.,Veverka, V.,Novotna, P.,Collinsova, M.,Urbanova, M.,Moody, N.R.,Turkenburg, J.P.,Jiracek, J.,Brzozowski, A.M.,Zakova, L.
An Insight Into Structural and Biological Relevance of the T/R Transition of the B-Chain N-Terminus in Human Insulin.
Biochemistry, 53:3392-, 2014

PubMed Abstract: The N-terminus of the B-chain of insulin may adopt two alternative conformations designated as the T- and R-states. Despite the recent structural insight into insulin-insulin receptor (IR) complexes, the physiological relevance of the T/R transition is still unclear. Hence, this study focused on the rational design, synthesis, and characterization of human insulin analogues structurally locked in expected R- or T-states. Sites B3, B5, and B8, capable of affecting the conformation of the N-terminus of the B-chain, were subjects of rational substitutions with amino acids with specific allowed and disallowed dihedral φ and ψ main-chain angles. α-Aminoisobutyric acid was systematically incorporated into positions B3, B5, and B8 for stabilization of the R-state, and N-methylalanine and d-proline amino acids were introduced at position B8 for stabilization of the T-state. IR affinities of the analogues were compared and correlated with their T/R transition ability and analyzed against their crystal and nuclear magnetic resonance structures. Our data revealed that (i) the T-like state is indeed important for the folding efficiency of (pro)insulin, (ii) the R-state is most probably incompatible with an active form of insulin, (iii) the R-state cannot be induced or stabilized by a single substitution at a specific site, and (iv) the B1-B8 segment is capable of folding into a variety of low-affinity T-like states. Therefore, we conclude that the active conformation of the N-terminus of the B-chain must be different from the "classical" T-state and that a substantial flexibility of the B1-B8 segment, where GlyB8 plays a key role, is a crucial prerequisite for an efficient insulin-IR interaction.

PubMed: 24819248
DOI: 10.1021/BI500073Z

Experimental method

X-RAY DIFFRACTION (1.7 Å)