Table 2.

Overview of characterized transcription regulators in thermoacidophilic archaea and their viruses.

Name	Family	Microbial or viral species	Gene number	Physiological role	Regulatory action	Reference
C68	AbrB	S. islandicus plasmid–virus pSSVx	ORFC68	(CRISPR-mediated) virus–host interactionsa	Activationa	(Contursi et al. 2011)
MerR	ArsR	S. solfataricus	SSO2688	Mercury resistance	Repression	(Schelert et al. 2006)
IdeR	DtxR	T. acidophilum	TA0872	Iron uptake and homeostasis	Repression	(Yeo et al. 2012; Yeo, Park and Lee 2014)
ArnA	FHA	S. acidocaldarius	Saci_1210	Motility	Repression	(Duan and He 2011; Reimann et al. 2012)
		S. tokodaii	ST0829
YtrA	GntR	S. acidocaldarius	Saci_1851	Expression of membrane proteins	Repression	(Lemmens et al. 2019b)
BarR	Lrp	S. acidocaldarius	Saci_2136	β-Alanine metabolism	Activation	(Liu et al. 2014a)
		S. tokodaii	ST1115
Lrp	Lrp	S. acidocaldarius	Saci_1588	Global regulation of metabolism and physiology	Dual	(Enoru-Eta et al. 2000; Vassart et al. 2013)
		S. solfataricus	SSO0606
LysM	Lrp	S. acidocaldarius	Saci_0752	Amino acid transport and metabolism	Activation	(Brinkman et al. 2002; Song et al. 2013)
		S. solfataricus	SSO0157
LrpB	Lrp	S. solfataricus	SSO2131	Regulation of pyruvate ferredoxin oxidoreductase and permeases	Dual	(Peeters et al. 2009; Peeters, Peixeiro and Sezonov 2013)
AbfR1	Lrs14	S. acidocaldarius	Saci_0446	Biofilm formation and motility	Dual	(Orell et al. 2013a; Li et al. 2017)
Sta1	Lrs14	S. solfataricus	SSO0048	Regulation of SIRV1 viral gene expression	Activation	(Kessler et al. 2006)
Lrs14	Lrs14	S. solfataricus	SSO1101	N.A.	Repression	(Bell and Jackson 2000)
Csa3a	MarR	S. islandicus	SiRe_0764	CRISPR spacer acquisition	Activation	(Liu et al. 2015)
BldR	MarR	S. solfataricus	SSO1352	Detoxification of aromatic compounds	Activation	(Fiorentino et al. 2007)
BldR2	MarR	S. solfataricus	SSO1082	Stress response to aromatic compounds	N.A.	(Fiorentino et al. 2011)
N.A.	MarR	S. tokodaii	ST1710	N.A.	N.A.	(Kumarevel et al. 2009)
MLPTv	MarR	T. volcanium	BAB59904b	N.A.	N.A.	(Liu, Walton and Rees 2010)
RbkR	MarRb	T. acidophilum	Ta1064	Riboflavin biosynthesis	Activationa	(Rodionova et al. 2017)
		M. yellowstonensis	EHP68448.1d
FadR	TetR	S. acidocaldarius	Saci_1107	Fatty acid and lipid metabolism	Repression	(Wang et al. 2019c)
HhcR	TrmB	M. yellowstonensis	H2C8P4d	Autotrophic metabolism	N.A.	(Leyn et al. 2015)
MalR	TrmB	S. acidocaldarius	Saci_1161	Maltose transport and metabolism	Activation	(Wagner et al. 2014)
ArnB	vWA	S. acidocaldarius	Saci_1211	Motility	Repression	(Reimann et al. 2012)
XylR	N.A.	S. acidocaldarius	Saci_2116	Arabinose/xylose transport and metabolism	Activation	(van der Kolk et al. 2020)
ArnR	N.A.	S. acidocaldarius	Saci_1180	Motility; type IV pili surface structures	Activation	(Lassak et al. 2013; Bischof, Haurat and Albers 2019)
ArnR1	N.A.	S. acidocaldarius	Saci_1171	Motility; type IV pili surface structures	Activation	(Lassak et al. 2013; Bischof, Haurat and Albers 2019)
CopR/CopT	N.A.	S. solfataricus	SSO2652	Copper homeostasis	Repression	(Ettema et al. 2006; Villafane et al. 2009)
Fur	N.A.	T. volcanium	TVN0292	Oxidative stress	N.A.	(Minoshima et al. 2014)
SvtR	N.A.e	S. islandicus rod-shaped virus 1 (SIRV1)	ORF56b	Viral development	Repression	(Guillière et al. 2009)
RIP	N.A.e	Acidianus two-tailed virus (ATV)	ORF145	Global regulation of host transcription	Repression	(Sheppard et al. 2016)
Stf76	N.A.e	S. islandicus plasmid–virus pSSVx	ORF76	N.A.	N.A.	(Contursi et al. 2014)
F55	N.A.e	Sulfolobus spindle-shaped virus 1	Tlys	Viral lysogeny and UV induction	Repression	(Fusco et al. 2015)

N.A. = not applicable (unknown based on published information).

^aHypothesized;

^bUNIPROT number;

^cMultifunctional protein with enzymatic and transcription regulatory domains;

^dGenBank accession number;

^eViral regulators are often difficult to classify into a family because of a lack of homology.