Table 2.

Factors involved in ammonium and amino acid sensing and metabolism and their role in virulence, when compared to the respective wild-type (WT) strain, in the human pathogenic fungi Aspergillus fumigatus, Cryptococcus neoformans and Candida albicans (NC = not characterized).

		Homolog	Virulence	Homolog	Virulence	Homolog	Virulence
Nitrogen sensing and uptake
Mep3p	Ammonium permease	MeaA	NC	Amt1	WT (Rutherford et al., 2008)	Mep1p	NC
Mep2p	Ammonium permease	Afu1g10930	NC	Amt2	WT (Rutherford et al., 2008)	Mep2p	NC
Ssy1p	Amino acid sensor	-	-	-	-	Csy1p	NC
Gap1p	Nitrogen sensor and amino acid permease	Afu7g04290	NC	Aap4	Avirulent (Cruz Martho et al., 2016)	Gap2p	NC
				Aap5
Tor1p, Tor2p	Protein kinase, major nitrogen sensor	TorA	NC	Tor1	NC	Tor1p	NC
Sit4p	Protein phosphatase	SitA	Avirulent (Bom et al., 2015)	NC	NC	Sit4p	Attenuated (Lee et al., 2004)
Rhb1p	GTPase	RhbA	Attenuated (Panepinto et al., 2003)	NC	NC	Rhb1p	NC
Nitrogen catabolite repression (NCR)
-	Co-repressor	NmrA	NC	-	-	-	-
Gat1p	GATA-type transcription factor	AreA	WT (Hensel et al., 1998)	Gat1	WT (McClelland et al., 2005)	Gat1p	Avirulent (Limjindaporn et al., 2003)
Gln3p	GATA-type transcription factor	-	-	-	-	Gln3p	Attenuated (Liao et al., 2008)
Gzf3p	GATA-type transcription factor	AreB	NC	-	-	Gzf3p	NC
-	Transcription factor	MeaB	NC	-	-	-	-
Additional factors involved in NCR
Dur1p	Urease	Afu1g04560 (UreB)	NC	Ure1	Attenuated (Cox et al., 2000)	Dur1p	NC
Dur2p		Afu2g12900 (UreD)				Dur2p
Yps3p	Aspartic proteinase	OpsB	NC	-	-	Sap1p	Attenuated (Hube et al., 1997)
Yps3p	Aspartic proteinase	OpsB	NC	-	-	Sap2p	Attenuated (Hube et al., 1997)
Yps3p	Aspartic proteinase	OpsB	NC	-	-	Sap3p	Attenuated (Hube et al., 1997)
Yps3p, Bar1p	Aspartic proteinases	OpsB	NC	-	-	Sap4p, Sap5p, Sap6p	Attenuated/Triple mutant only (Hube et al., 1997)
-	Metalloproteinase	Mep/Aspf5	NC	Mpr1	Attenuated (Vu et al., 2014)	-	-
Urc2p	Transcription factor	PrtT	WT (Bergmann et al., 2009; Sharon et al., 2009)	NC	NC	Zcf19p	NC