1Z24

The molecular structure of insecticyanin from the tobacco hornworm Manduca sexta L. at 2.6 A resolution.

Summary for 1Z24

• Entry DOI: 10.2210/pdb1z24/pdb
• Descriptor: Insecticyanin A form, BILIVERDIN IX GAMMA CHROMOPHORE (2 entities in total)
• Functional Keywords: blue biliprotein, ins-a, chromophore binding., lipid binding protein
• Biological source: Manduca sexta (tobacco hornworm)
• Cellular location: Secreted: P00305
• Total number of polymer chains: 1
• Total formula weight: 21988.67

Authors

Holden, H.M.,Rypniewski, W.R.,Law, J.H.,Rayment, I. (deposition date: 2005-03-07, release date: 2005-04-05, Last modification date: 2024-10-30)

Primary citation

Holden, H.M.,Rypniewski, W.R.,Law, J.H.,Rayment, I.
The molecular structure of insecticyanin from the tobacco hornworm Manduca sexta L. at 2.6 A resolution.
Embo J., 6:1565-1570, 1987

PubMed Abstract: Insecticyanin, a blue biliprotein isolated from the tobacco hornworm Manduca sexta L., is involved in insect camouflage. Its three-dimensional structure has now been solved to 2.6 A resolution using the techniques of multiple isomorphous replacement, non-crystallographic symmetry averaging about a local 2-fold rotation axis and solvent flattening. All 189 amino acids have been fitted to the electron density map. The map clearly shows that insecticyanin is a tetramer with one of its molecular 2-fold axes coincident to a crystallographic dyad. The individual subunits have overall dimensions of 44 A X 37 A X 40 A and consist primarily of an eight-stranded anti-parallel beta-barrel flanked on one side by a 4.5-turn alpha-helix. Interestingly the overall three-dimensional fold of the insecticyanin subunit shows remarkable similarity to the structural motifs of bovine beta-lactoglobulin and the human serum retinol-binding protein. The electron density attributable to the chromophore is unambiguous and shows that it is indeed the gamma-isomer of biliverdin. The biliverdin lies towards the open end of the beta-barrel with its two propionate side chains pointing towards the solvent and it adopts a rather folded conformation, much like a heme.

PubMed: 3608987

Experimental method

X-RAY DIFFRACTION (2.6 Å)