Price Nathan D, Papin Jason A, Palsson Bernhard Ø
Department of Bioengineering, University of California at San Diego, La Jolla, California 92093, USA.
Genome Res. 2002 May;12(5):760-9. doi: 10.1101/gr.218002.
The capabilities of genome-scale metabolic networks can be described through the determination of a set of systemically independent and unique flux maps called extreme pathways. The first study of genome-scale extreme pathways for the simultaneous formation of all nonessential amino acids or ribonucleotides in Helicobacter pylori is presented. Three key results were obtained. First, the extreme pathways for the production of individual amino acids in H. pylori showed far fewer internal states per external state than previously found in Haemophilus influenzae, indicating a more rigid metabolic network. Second, the degree of pathway redundancy in H. pylori was essentially the same for the production of individual amino acids and linked amino acid sets, but was approximately twice that of the production of the ribonucleotides. Third, the metabolic network of H. pylori was unable to achieve extensive conversion of amino acids consumed to the set of either nonessential amino acids or ribonucleotides and thus diverted a large portion of its nitrogen to ammonia production, a potentially important result for pH regulation in its acidic habitat. Genome-scale extreme pathways elucidate emergent system-wide properties. Extreme pathway analysis is emerging as a potentially important method to analyze the link between the metabolic genotype and its phenotypes.
基因组规模代谢网络的能力可以通过确定一组称为极端途径的系统独立且独特的通量图来描述。本文首次对幽门螺杆菌中同时合成所有非必需氨基酸或核糖核苷酸的基因组规模极端途径进行了研究。获得了三个关键结果。首先，幽门螺杆菌中单个氨基酸产生的极端途径显示，每个外部状态的内部状态比先前在流感嗜血杆菌中发现的要少得多，这表明其代谢网络更为僵化。其次，幽门螺杆菌中单个氨基酸和相关氨基酸集产生的途径冗余度基本相同，但约为核糖核苷酸产生途径冗余度的两倍。第三，幽门螺杆菌的代谢网络无法将消耗的氨基酸广泛转化为非必需氨基酸或核糖核苷酸，因此将大部分氮转移到氨的产生中，这对于其酸性栖息地的pH调节可能是一个重要结果。基因组规模极端途径阐明了全系统出现的特性。极端途径分析正在成为一种潜在的重要方法，用于分析代谢基因型与其表型之间的联系。
