PDBsum entry 1ce3

Protease inhibitor

PDB id: 1ce3

Contents

Protein chain

54 a.a. *

* Residue conservation analysis

PDB id:

1ce3

Name:

Protease inhibitor

Title:

Putative ancestral protein encoded by a single sequence repeat of the multidomain proteinase inhibitor from nicotiana alata

Structure:

Api. Chain: a. Fragment: first sequence repeat. Engineered: yes. Other_details: single sequence repeat from a multidomain proteinase inhibitor

Source:

Nicotiana alata. Persian tobacco. Organism_taxid: 4087. Expressed in: escherichia coli. Expression_system_taxid: 562

NMR struc:

20 models

Authors:

M.J.Scanlon,M.C.S.Lee,M.A.Anderson,D.J.Craik

Key ref:

M.J.Scanlon et al. (1999). Structure of a putative ancestral protein encoded by a single sequence repeat from a multidomain proteinase inhibitor gene from Nicotiana alata. Structure, 7, 793-802. PubMed id: 10425681 DOI: 10.1016/S0969-2126(99)80103-8

Date:

14-Mar-99 Release date: 27-Mar-99

Protein chain

Q40378  (Q40378_NICAL) -  Proteinase inhibitor from Nicotiana alata

Seq: 397 a.a.

Struc: 54 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

DOI no: 10.1016/S0969-2126(99)80103-8

Structure 7:793-802 (1999)

PubMed id: 10425681

Structure of a putative ancestral protein encoded by a single sequence repeat from a multidomain proteinase inhibitor gene from Nicotiana alata.

M.J.Scanlon, M.C.Lee, M.A.Anderson, D.J.Craik.

ABSTRACT

BACKGROUND: The ornamental tobacco Nicotiana alata produces a series of proteinase inhibitors (PIs) that are derived from a 43 kDa precursor protein, NaProPI. NaProPI contains six highly homologous repeats that fold to generate six separate structural domains, each corresponding to one of the native PIs. An unusual feature of NaProPI is that the structural domains lie across adjacent repeats and that the sixth PI domain is generated from fragments of the first and sixth repeats. Although the homology of the repeats suggests that they may have arisen from gene duplication, the observed folding does not appear to support this. This study of the solution structure of a single NaProPI repeat (aPI1) forms a basis for unravelling the mechanism by which this protein may have evolved. RESULTS: The three-dimensional structure of aPI1 closely resembles the triple-stranded antiparallel beta sheet observed in each of the native PIs. The five-residue sequence Glu-Glu-Lys-Lys-Asn, which forms the linker between the six structural domains in NaProPI, exists as a disordered loop in aPI1. The presence of this loop in aPI1 results in a loss of the characteristically flat and disc-like topography of the native inhibitors. CONCLUSIONS: A single repeat from NaProPI is capable of folding into a compact globular domain that displays native-like PI activity. Consequently, it is possible that a similar single-domain inhibitor represents the ancestral protein from which NaProPI evolved.

Selected figure(s)

Figure 4.
Figure 4. Schematic diagram of the secondary structural elements of aPI1 showing the NOEs betweenβ strands (double-headed arrows) and the position of proposed hydrogen bonds (broken lines).

The above figure is reprinted by permission from Cell Press: Structure (1999, 7, 793-802) copyright 1999.

Figure was selected by an automated process.