The rubredoxin domain of AtHSCB modulates Fe-S synthesis and Fe translocation from roots to shoots in Arabidopsis.

BALPARDA, M.; ARMAS, ALEJANDRO M.; DIEGO FABIAN GOMEZ CASATI; PAGANI, MARIA A.

Virtual

Congreso; RAFV Conference 2021, XXXIII Argentinian meeting of Plant Physiology; 2021

Sociedad Argentina de Fisiología Vegetal (SAFV)

In yeast, flies and vertebrates there is anintimate connection between Fe homeostasis and Fe-S cluster formation. We haveshown that altered levels of HSCB (co-chaperone, involved in the Fe-S clusterbiogenesis) affect iron translocation from roots to shoots in Arabidopsis. Inthis work we analyzed the role of the HSCB rubredoxin domain, suggested to bindFe ions or Fe-S clusters, by overexpressing rubAtHSCB –the truncated form ofthe protein- in wild type and hscbgenetic backgrounds, rubHSCB-wt and rubHSCB-hscb respectively. Under Fesufficient conditions, there were alterations in root and shoot Fe contents inboth rubHSCB-wt and rubHSCB-hscb lines, however these changeswere milder than in knockdown or complete HSCB overexpressing plants. Expressionand activity of the main Fe uptake system were correlated with the altered Fecontents. Shoot activities of the Fe-S enzymes ACO and SDH in rubHSCB-wt and rubHSCB-hscb lines were lower than in wt lines, but higher than in hscbor HSCB overexpressing lines. All these changes point to a regulatory effect ofthe rubredoxin domain over HSCB activity. We confirmed, by recombinantexpression and in vitro reactions,that rubHSCB protein induced a lower ATPase activity in its partner protein ofthe Fe-S biosynthesis pathway, the chaperone HSCA1, than the complete HSCBprotein.