Structural and functional comparison of hemoglobin Glb2-1 of Lotus japonicus with Glb1-1 and leghemoglobins

Esquinas-Ariza, Rosa M. ; Villar, Irene ; Minguillón, Samuel ; Zamarreño, Ángel ; Pérez-Rontomé, Carmen ; Reeder, Brandon J. ; Sandal, Niels ; Yan, Deng ; García-Mina, José M. ; Duanmu, Deqiang ; Martínez-Júlvez, Marta (Universidad de Zaragoza) ; Becana, Manuel

Resumen: The legume Lotus japonicus expresses nine hemoglobins, including leghemoglobins (Lbs), class 1 phytoglobin (Glb1-1), and an unusual phytoglobin (Glb2-1). Quantitative PCR, proteomics, and plant mutant analyses indicated that Glb2-1 is mainly present in nodules without replacing Lb function, but is also in roots and photosynthetic tissues. Comparison of hormonal profiles of the knock-out mutants glb1-1, glb2-1, and glb1-1/2-1 showed that Glb1-1 and Glb2-1 have distinct functions. The increase of salicylic acid in the leaves of glb1-1 revealed a role of Glb1-1 in the defense response, which was corroborated by accumulation of pipecolic acid, a metabolite involved in plant immunity. In contrast, the decrease of bioactive jasmonoyl-isoleucine in glb2-1 was consistent with a role of Glb2-1 in the plant's reproductive stage. The mutants also showed changes in cytokinins, gibberellins, and polyamines, but without clear distinctive patterns. The crystal structure of Glb2-1 was determined to 1.6 Å resolution and compared with those of soybean Lba and Arabidopsis Glb1. In combination with mutant versions of Glb2-1, residues Tyr31, His64, and Cys65 were identified as critical for O2-binding stability. Spectral changes in heme coordination when Tyr31 is substituted for Phe highlights the importance of the residue at the B10 position for Lb and Glb function.

Idioma: Inglés

DOI: 10.1093/jxb/eraf434

Año: 2025

Publicado en: Journal of Experimental Botany (2025), [17 pp.]
ISSN: 0022-0957

Financiación: info:eu-repo/grantAgreement/ES/AEI/PID2023-147035NB-I00
Financiación: info:eu-repo/grantAgreement/ES/DGA/A09-23R
Financiación: info:eu-repo/grantAgreement/ES/DGA/E35-23R
Financiación: info:eu-repo/grantAgreement/ES/MICINN/PID2020-113985GB-I00

Tipo y forma: Artículo (Versión definitiva)

Área (Departamento): Área Bioquímica y Biolog.Mole. (Dpto. Bioq.Biolog.Mol. Celular)