Recent advances in the Suf Fe–S cluster biogenesis pathway: Beyond the Proteobacteria

Abstract

Fe-S clusters play critical roles in cellular function throughout all three kingdoms of life. Consequently, Fe-S cluster biogenesis systems are present in most organisms. The Suf (sulfur formation) system is the most ancient of the three characterized Fe-S cluster biogenesis pathways, which also include the Isc and Nif systems. Much of the first work on the Suf system took place in Gram-negative Proteobacteria used as model organisms. These early studies led to a wealth of biochemical, genetic, and physiological information on Suf function. From those studies we have learned that SufB functions as an Fe-S scaffold in conjunction with SufC (and in some cases SufD). SufS and SufE together mobilize sulfur for cluster assembly and SufA traffics the complete Fe-S cluster from SufB to target apo-proteins. However, recent progress on the Suf system in other organisms has opened up new avenues of research and new hypotheses about Suf function. This review focuses primarily on the most recent discoveries about the Suf pathway and where those new models may lead the field.

Iron–Sulfur Cluster Biogenesis and Iron Homeostasis in Cyanobacteria

“…Compared with ISC system, SUF system is less widespread and is found only in archaea, most gram-positive bacteria, the chloroplasts of plants, and green algae (Takahashi et al, 1986(Takahashi et al, , 1991Takahashi and Tokumoto, 2002;Albrecht et al, 2010;Santos et al, 2014;Selbach et al, 2014). In E. coli, the SUF system is activated only in response to conditions of oxidative stress or Fe starvation (Outten et al, 2004;Outten, 2015). During evolution, cyanobacteria choose SUF as their major system for Fe-S cluster biosynthesis (Balasubramanian et al, 2006;Ayala-Castro et al, 2008;Outten, 2015), and all core suf genes cannot be knocked out completely in the cyanobacterium Synechocystis 6803 (Tirupati et al, 2004;Balasubramanian et al, 2006;Zang et al, 2017).…”

[Fe–S] cluster assembly in the apicoplast and its indispensability in mosquito stages of the malaria parasite

“…In bacteria, three distinct sets of factors/enzymes encoded as operons assemble [Fe–S] clusters; the bacterial [Fe–S] cluster formation (ISC), sulfur mobilization (SUF), and nitrogen fixation (NIF) operons encode proteins that are components of the ISC, SUF, and NIF assembly systems . The ISC system is the major [Fe–S] biogenesis system with the SUF system being activated under iron starvation or oxidative stress . However, SUF is the primary assembly pathway in organisms such as Mycobacterium tuberculosis and cyanobacteria .…”

Bacterial Electron Transfer Chains Primed by Proteomics

“…The pathway is named after two adjacent arginines that typically are located about 20 positions after the translation start. Preassembly within the cytoplasm may include the insertion of iron-sulphur clusters synthesised by the Suf and ISC systems (Blanc, Gerez, & Ollagnier de Choudens, 2015;Kim, Bothe, Alderson, & Markley, 2015;Kim, Jang, et al, 2015;Wayne Outten, 2015;Yokoyama & Leimkühler, 2015) or of the molybdopterin cofactor, which is the catalytic heart of a wide variety of respiratory enzymes, including formate dehydrogenase and nitrate reductase (Grimaldi, Schoepp-Cothenet, Ceccaldi, Guigliarelli, & Magalon, 2013). Translation at the ribosomes and transport through the membrane can be intimately coupled by action of the signal recognition particle, trigger factor and of the DnaK and GroeEL protein-folding apparatus (Castani e-Cornet, Bruel, & Genevaux, 2014;Saraogi & Shan, 2014).…”