Structural analysis of three peptides related to the transmambranic helix VI of AT1 receptor

de Noronha, Samuel Marcos Ribeiro; Corrêa, Silvana Aparecida Alves; Poletti, Erick Fernando; Lopes, Douglas Duarte; da Silva, Caroline Corrêa; Sforça, Mauricio Luis; Shimuta, Suma Imura; Zanchin, Nilson Ivo Tonin; Nakaie, Clovis Ryuichi; da Silva, Ismael Dale Cotrim Guerreiro

doi:10.1016/j.npep.2009.11.006

« Previous Next »Neuropeptides
Volume 44, Issue 2 , Pages 115-118, April 2010

Structural analysis of three peptides related to the transmambranic helix VI of AT1 receptor☆☆☆

Samuel Marcos Ribeiro de Noronha
- Ginecologia Molecular/Ginecologia, UNIFESP-R. Pedro de Toledo, 791 – 4o. Andar, V. Clementino, CEP04039032 Sao Paulo, SP, Brazil
- Corresponding author. Address: Molecular Gynecology Laboratory, Gynecology Department, Federal University of Sao Paulo, Rua Pedro de Toledo, 781 – 4th floor, Sao Paulo, 04039-032 SP, Brazil. Tel.: +55 55791534; fax: +55 11 55793321.
Silvana Aparecida Alves Corrêa
- Ginecologia Molecular/Ginecologia, UNIFESP-R. Pedro de Toledo, 791 – 4o. Andar, V. Clementino, CEP04039032 Sao Paulo, SP, Brazil
Erick Fernando Poletti
- Dep. Biofisica-R. Botucatu, 840 – 7o. Andar, V. Clementino, Sao Paulo, SP, Brazil
Douglas Duarte Lopes
- Dep. Biofisica-R. Botucatu, 840 – 7o. Andar, V. Clementino, Sao Paulo, SP, Brazil
Caroline Corrêa da Silva
- Dep. Biofisica-R. Botucatu, 840 – 7o. Andar, V. Clementino, Sao Paulo, SP, Brazil
Mauricio Luis Sforça
- Laboratorio Nacional de Luz Sincroton-Rua Giuseppe Maximo Scolfaro, 10000-Polo II de Alta Tecnologia de Campinas-Campinas, SP, Brazil
Suma Imura Shimuta
- Dep. Biofisica-R. Botucatu, 840 – 7o. Andar, V. Clementino, Sao Paulo, SP, Brazil
Nilson Ivo Tonin Zanchin
- Laboratorio Nacional de Luz Sincroton-Rua Giuseppe Maximo Scolfaro, 10000-Polo II de Alta Tecnologia de Campinas-Campinas, SP, Brazil
Clovis Ryuichi Nakaie
- Dep. Biofisica-R. Botucatu, 840 – 7o. Andar, V. Clementino, Sao Paulo, SP, Brazil
Ismael Dale Cotrim Guerreiro da Silva
- Ginecologia Molecular/Ginecologia, UNIFESP-R. Pedro de Toledo, 791 – 4o. Andar, V. Clementino, CEP04039032 Sao Paulo, SP, Brazil

published online 14 December 2009.

Abstract

Introduction

Angiotensin II (AII) is the main active product of the renin angiotensin system. Better known effects of AII are via AT1 receptor (AT1R). Expression of AT1R mutants (L265D and L262D) in CHO cells increased cAMP formation when compared to CHO cells expressing the wild type (WT) AT1R. Morphological transformation of CHO cells transfected with mutants correlated with their increased cAMP formation. DNA synthesis was inhibited in these cells too, indicating that cAMP promotes inhibitory effects on transfected CHO cells growth and causes their morphological change from a tumorigenic phenotype to a non-tumorigenic one.

Objectives

To assess the importance of leucine 262 and 265 in determining AT1R structure by means of a comparative structural analysis of two mutant peptides and of a wild-type fragment.

Methodology

Three peptides had their conformation compared by circular dichroism (CD): L262D_259–272, L265D_259–272 (mutants) and WT_260–277.

Results

Secondary structures were: β-turn for WT and L262D and random coil for L265D.

Conclusions

Strong correlation was found in the results of biochemical, cellular and structural approaches used to compare WT AT1R to mutant types. Random coil structure of the L265D mutant may be a key point to explain those changes observed in biochemical (binding and signal transduction) and proliferation assays (Correa et al., 2005). β-Turn formation is an important step during early protein folding and this secondary simple structure is present in L262D and WT, but not in L265D. Therefore, leucine 265 seems to play a crucial role in determining an entirely functional AT1R.

Abbreviations: RAS, renin angiotensin system, ACE, angiotensin converting Enzyme, AII, angiotensin II, AI, angiotensin I, AT₁R, angiotensin II type 1 receptor, CD, circular dichroism spectroscopy