Arnau J, Jørgensen F, Madsen S M, Vrang A, Israelsen H
Biotechnological Institute, Hørsholm, Denmark.
J Bacteriol. 1997 Sep;179(18):5884-91. doi: 10.1128/jb.179.18.5884-5891.1997.
The Lactococcus lactis pfl gene, encoding pyruvate formate-lyase (PFL), has been cloned and characterized. The deduced amino acid sequence of the L. lactis PFL. protein showed high similarity to those of other bacterial PFL proteins and included the conserved glycine residue involved in posttranslational activation of PFL. The genetic organization of the chromosomal pfl region in L. lactis showed differences from other characterized pfl loci, with an upstream open reading frame independently transcribed in the same orientation as the pfl gene. The gene coding for PFL-activase (act), normally found downstream of pfl, was not identified in L. lactis. Analysis of pfl expression showed a strong induction under anaerobiosis at the transcriptional level independent of the growth medium used. During growth with galactose, pfl showed the highest levels of expression. Constructed L. lactis pfl strains were unable to produce formate under anaerobic growth. Higher levels of diacetyl and acetoin were produced anaerobically in the constructed Lactococcus lactis subsp. lactis biovar diacetylactis pfl strain.
编码丙酮酸甲酸裂解酶（PFL）的乳酸乳球菌pfl基因已被克隆并进行了表征。乳酸乳球菌PFL蛋白的推导氨基酸序列与其他细菌的PFL蛋白具有高度相似性，并且包含参与PFL翻译后激活的保守甘氨酸残基。乳酸乳球菌中染色体pfl区域的基因组织与其他已表征的pfl基因座不同，其上游开放阅读框以与pfl基因相同的方向独立转录。通常位于pfl下游的编码PFL激活酶（act）的基因在乳酸乳球菌中未被鉴定到。对pfl表达的分析表明，在厌氧条件下，转录水平上有强烈的诱导作用，且与所用生长培养基无关。在以半乳糖生长期间，pfl表现出最高水平的表达。构建的乳酸乳球菌pfl菌株在厌氧生长条件下无法产生甲酸。在构建的乳酸乳球菌乳酸亚种双乙酰变种pfl菌株中，厌氧条件下产生了更高水平的双乙酰和乙偶姻。
