SNZ3 Encodes a PLP Synthase Involved in Thiamine Synthesis in Saccharomyces cerevisiae

Abstract

Pyridoxal 5′-phosphate (the active form of vitamin B 6 ) is a cofactor that is important for a broad number of biochemical reactions and is essential for all forms of life. Organisms that can synthesize pyridoxal 5′-phosphate use either the deoxyxylulose phosphate-dependent or -independent pathway, the latter is encoded by a two-component pyridoxal 5′-phosphate synthase. Saccharomyces cerevisiae contains three paralogs of the two-component SNZ/SNO pyridoxal 5′-phosphate synthase. Past work identified the biochemical activity of Snz1p , Sno1p and provided in vivo data that SNZ1 was involved in pyridoxal 5′-phosphate biosynthesis. Snz2p and Snz3p were considered redundant isozymes and no growth condition requiring their activity was reported. Genetic data herein showed that either SNZ2 or SNZ3 are required for efficient thiamine biosynthesis in Saccharomyces cerevisiae . Further, SNZ2 or SNZ3 alone could satisfy the cellular requirement for pyridoxal 5′-phosphate (and thiamine), while SNZ1 was sufficient for pyridoxal 5′-phosphate synthesis only if thiamine was provided. qRT-PCR analysis determined that SNZ2 , 3 are repressed ten-fold by the presence thiamine. In total, the data were consistent with a requirement for PLP in thiamine synthesis, perhaps in the Thi5p enzyme, that could only be satisfied by SNZ2 or SNZ3 . Additional data showed that Snz3p is a pyridoxal 5′-phosphate synthase in vitro and is sufficient to satisfy the pyridoxal 5′-phosphate requirement in Salmonella enterica when the medium has excess ammonia.

Vitamin requirements and biosynthesis in Saccharomyces cerevisiae

“…In contrast to the SNZ1/SNO1 gene pair, which is located in the middle of the right arm of CHRXIII, SNZ2 / SNO2 and SNZ3 / SNO3 are found in subtelomeric regions of CHRXIV and VI, respectively, and are flanked by the thiamine biosynthetic genes THI12 and THI5 , respectively. Their increased expression upon thiamine depletion is consistent with the role of PLP in thiamine biosynthesis (Paxhia & Downs, ). The demonstration that Snz proteins can directly interact with Thi5 proteins (Rodriguez‐Navarro et al, ) further shows the interaction of pyridoxine and thiamine biosynthesis (Figure ).…”

“…Their increased expression upon thiamine depletion is consistent with the role of PLP in thiamine biosynthesis (Paxhia & Downs, 2019). The demonstration that Snz proteins can directly interact with Thi5 proteins (Rodriguez-Navarro et al, 2002) further shows the interaction of pyridoxine and thiamine biosynthesis ( Figure 1).…”

Pyridoxal Reductase, PdxI, Is Critical for Salvage of Pyridoxal in Escherichia coli

“…During the study of the biosynthesis, homeostasis, and metabolic network of vitamin B 6 in Escherichia coli and Salmonella enterica (16)(17)(18), we found that E. coli strains lacking pdxJ had different PL requirements than those lacking pdxH. This result was unexpected given that both lesions abolish PLP biosynthesis.…”

Comparative Genomics Supports That Brazilian Bioethanol Saccharomyces cerevisiae Comprise a Unified Group of Domesticated Strains Related to Cachaça Spirit Yeasts

“…These two enzymes, respectively, control successive catalytic steps for the synthesis of vitamin B6 (PLP) (Rodriguez-Navarro et al, 2002). SNO2(3)/SNZ2(3) are located in subtelomeric clusters together with the thiamin biosynthetic gene THI5(12), and their products physically interact in a complex that likely channels the PLP for thiamin production (Rodriguez-Navarro et al, 2002;Paxhia and Downs, 2019). In accordance with previous observations (Argueso et al, 2009;Stambuk et al, 2009), our analysis of gene CNVs revealed that all strains in the bioethanol dataset (exempting one cachaça strain) have increased copies of the SNO2(3)/SNZ2(3) region when compared with S288C.…”