Heterogeneity of the serine synthetic pathway in Entamoeba species

• Phosphoserine phosphatase (PSP) is the final enzyme in serine biosynthesis.
• PSP has been identified and characterized in a protozoan parasite of reptiles, Entamoeba invadens.
• E. invadens likely gained PSP gene by lateral gene transfer.
• Primate Entamoeba species including E. histolytica apparently lack PSP.
• Heterogeneity in the serine biosynthetic pathway exists in the genus Entamoeba.

Phosphoserine phosphatase (PSP) catalyzes the third step of the phosphorylated serine biosynthetic pathway, and occurred multiple times in evolution, while enzymes catalyzing the first and second steps in the pathway have single respective origins. In the present study, we examined the existence of PSP among genus Entamoeba including a human enteric parasite, Entamoeba histolytica. E. histolytica as well as majority of Entamoeba species have the first and second enzymes, but lacks PSP. In contrast, a reptilian enteric parasite, Entamoeba invadens possesses canonical PSP. Thus, there are variations in the existence of the serine biosynthetic ability among Entamoeba species.

Figure optionsDownload high-quality image (118 K)Download as PowerPoint slidePhosphoserine phosphatase (PSP) was found to exist in Entamoeba invadens but not in other Entamoeba species including E. histolytica, strongly suggesting marked differences in the serine biosynthetic ability in the genus Entamoeba.