Structural and enzymatic analyses of Anabaena heterocyst‐specific alkaline invertase InvB

Abstract

Anabaena sp. PCC 7120 encodes two alkaline/neutral invertases, namely InvA and InvB. Following our recently reported InvA structure, here we report the crystal structure of the heterocyst-specific InvB. Despite sharing an overall structure similar to InvA, InvB possesses a much higher catalytic activity. Structural comparisons of the catalytic pockets reveal that Arg430 of InvB adopts a different conformation, which may facilitate the deprotonation of the catalytic residue Glu415. We propose that the higher activity may be responsible for the vital role of InvB in heterocyst development and nitrogen fixation. Furthermore, phylogenetic analysis combined with activity assays also suggests the role of this highly conserved arginine in plants and cyanobacteria, as well as some proteobacteria living in highly extreme environments.

Evolutionary Conservation and Expression Patterns of Neutral/Alkaline Invertases in Solanum

“…It was recently reported that three amino acid residues (D188, E414, and Arg430) were found to be associated with catalytic activity, established in crystal-structure comparison and enzymatic assays of CINs (InvA and InvB), which is isolated from the cyanobacterium Anabaena [22,23]. In the current paper, these three conserved residues were also observed in all CIN genes within five Solanum plants on the basis of sequence alignment, except that SmCIN08 was missing D188, and SmCIN07 lacked the E414 and Arg430 residues ( Figure 2 and Table S1).…”

“…In addition, analysis of the crystal structures of CINs (InvA and InvB) in a cyanobacterium revealed overall structural similarity of InvA and InvB invertases [22,23]. They share an (α/α)6-barrel core structure composed of 12 α-helices and an insertion of three helices.…”

“…Two putative catalytic residues, Asp188 and Glu414 in InvA, and InvA' stringent substrate specificity towards the α1, 2-glycosidic bond of sucrose were further proposed [22]. In InvB, the Arg430 residue possesses different conformation, likely facilitating the deprotonation of catalytic residue Glu415 [23]. CINs are evolutionarily and functionally more stable compared with CWINs and VINs according to the phylogenetic relationship and functional genomic analysis, which may reflect their roles in maintaining cytosolic sugar homeostasis for cellular function [24].…”

Quantitative Proteomics Reveals the Protein Regulatory Network of Anabaena sp. PCC 7120 under Nitrogen Deficiency

“…However, heterocysts, as a result of the photosystem switch, rely on neighboring cells to provide NADPH for the nitrogen fixation process through the oxidative pentose phosphate pathway (OPP) and to provide sucrose or glycogen to maintain their metabolism. , Two different enzymes catalyze the degradation of sucrose: sucrose synthase (SUS) and invertase (Inv). SUS can reversibly decompose sucrose into ADP-glucose or UDP-glucose and fructose, while sucrose invertase (Inv) can unidirectionally catalyze the hydrolysis of sucrose into fructose and glucose . Inv plays a major role when cells have high carbon and energy needs .…”

Ação das enzimas celulase, invertase, pectinase e xilanase na produção de vinhos – uma revisão sistemática da literatura / Activity of celulase, invertase, pectinase and xylanase enzymes in wine production - a systematic literature review

“…A catálise da hidrólise irreversível da sacarose libera glicose e frutose (XIE et al, 2018), que podem ser utilizadas pelos microrganismos durante a fermentação alcoólica para produzir etanol (TRAN et al, 2020). Devido a isso, é considerada como enzima chave do metabolismo do açúcar nas uvas (HOVASSE et al, 2016).…”