1S7P

Solution structure of thermolysin digested microcin J25

Summary for 1S7P

• Entry DOI: 10.2210/pdb1s7p/pdb
• Related: 1Q71
• Descriptor: microcin J25 (2 entities in total)
• Functional Keywords: thermolysin digested microcin j25, t-mccj25, thermolysin digest, two-chain peptide, steric link, antimicrobial protein, antibiotic
• Biological source: Escherichia coli; More
• Cellular location: Secreted: Q9X2V7 Q9X2V7
• Total number of polymer chains: 2
• Total formula weight: 2144.36

Authors

Rosengren, K.J.,Blond, A.,Afonso, C.,Tabet, J.C.,Rebuffat, S.,Craik, D.J. (deposition date: 2004-01-30, release date: 2004-06-15, Last modification date: 2024-10-30)

Primary citation

Rosengren, K.J.,Blond, A.,Afonso, C.,Tabet, J.C.,Rebuffat, S.,Craik, D.J.
Structure of thermolysin cleaved microcin J25: extreme stability of a two-chain antimicrobial peptide devoid of covalent links
Biochemistry, 43:4696-4702, 2004

PubMed Abstract: The structure of a two-chain peptide formed by the treatment of the potent antimicrobial peptide microcin J25 (MccJ25) with thermolysin has been characterized by NMR spectroscopy and mass spectrometry. The native peptide is 21 amino acids in size and has the remarkable structural feature of a ring formed by linkage of the side chain of Glu8 to the N-terminus that is threaded by the C-terminal tail of the peptide. Thermolysin cleaves the peptide at the Phe10-Val11 amide bond, but the threading of the C-terminus through the N-terminal ring is so tight that the resultant two chains remain associated both in the solution and in the gas phases. The three-dimensional structure of the thermolysin-cleaved peptide derived using NMR spectroscopy and simulated annealing calculations has a well-defined core that comprises the N-terminal ring and the threading C-terminal tail. In contrast to the well-defined core, the newly formed termini at residues Phe10 and Val11 are disordered in solution. The C-terminal tail is associated to the ring both by hydrogen bonds stabilizing a short beta-sheet and by hydrophobic interactions. Moreover, unthreading of the tail through the ring is prevented by the bulky side chains of Phe19 and Tyr20, which flank the octapeptide ring. This noncovalent two-peptide complex that has a remarkable stability in solution and in highly denaturing conditions and that survives in the gas phase is the first example of such a two-chain peptide lacking disulfide or interchain covalent bonds.

PubMed: 15096038
DOI: 10.1021/bi0361261

Experimental method

SOLUTION NMR