Analysis of the amino acid sequences of plant Bowman-Birk inhibitors

Prakash, Balaji and Selvaraj, S and Murthy, MRN and Sreerama, YN and Rao, D Rajagopal and Gowda, Lalitha R (1996) Analysis of the amino acid sequences of plant Bowman-Birk inhibitors. In: Journal of Molecular Evolution, 42 (5). pp. 560-569.

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Abstract

Plant seeds contain a large number of protease inhibitors of animal, fungal, and bacterial origin. One of the well-studied families of these inhibitors is the Bowman-Birk family(BBI). The BBIs from dicotyledonous seeds are 8K, double-headed proteins. In contrast, the 8K inhibitors from monocotyledonous seeds are single headed. Monocots also have a 16K, double-headed inhibitor. We have determined the primary structure of a Bowman-Birk inhibitor from a dicot, horsegram, by sequential edman analysis of the intact protein and peptides derived from enzymatic and chemical cleavage. The 76-residue-long inhibitor is very similar to that ofMacrotyloma axillare. An analysis of this inhibitor along with 26 other Bowman-Birk inhibitor domains (MW 8K) available in the SWISSPROT databank revealed that the proteins from monocots and dicots belong to related but distinct families. Inhibitors from monocots show larger variation in sequence. Sequence comparison shows that a crucial disulphide which connects the amino and carboxy termini of the active site loop is lost in monocots. The loss of a reactive site in monocots seems to be correlated to this. However, it appears that this disulphide is not absolutely essential for retention of inhibitory function. Our analysis suggests that gene duplication leading to a 16K inhibitor in monocots has occurred, probably after the divergence of monocots and dicots, and also after the loss of second reactive site in monocots.

Item Type:	Journal Article
Publication:	Journal of Molecular Evolution
Publisher:	Springer
Additional Information:	Copyright of this article belongs to Springer.
Keywords:	Bowman-Birk;Inhibitors;Sequence analysis;Monocotyledon; Dicotyledon;Gene duplication;Dolichos biflorus.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	20 Jan 2010 11:24
Last Modified:	19 Sep 2010 05:51
URI:	http://eprints.iisc.ac.in/id/eprint/24774

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