Table 1. Protein set used in this analysis.

Solubility in E. coli reflects testing; ND, no data. Expression and solubililty ratings reflect small-scale expression using WEPRO1240H. Expression key: −, less than 15 µg µl⁻¹; +, less than 0.30 µg µl⁻¹; ++, less than 0.75 µg µl⁻¹ but greater than 0.30 µg µl⁻¹; +++ greater than 0.75 µg µl⁻¹ Solubility key: −, no soluble protein; +, less than 25% total protein soluble; ++, 25–75% total protein soluble; +++, greater than 75% total protein soluble.

Species	Accession ID	Sequence cloned	Annotation	Solubility in E. coli in vivo	Cell-free expression	Cell-free solubility
Anaplasma marginale	ACR67103.1	Full length	Major surface protein 2 variant 9H1	ND	+	−
Anaplasma marginale	ACR67104.1	Full length	Major surface protein 2	ND	−	−
Anaplasma marginale	ACR67105.1	Full length	Major surface protein 2 variant E6F7/1/2	ND	+	−
Bartonella henselae	YP_033889.1	Full length	UDP-3-O-(3-hydroxymyristoyl) N-acetylglucosamine deacetylase	Insoluble	+++	ND
Bartonella henselae	YP_032889.1	Full length	ABC transporter/ATP-binding protein	Insoluble	++	++
Bartonella henselae	YP_034187.1	Full length	Holliday junction DNA helicase B	Insoluble	++	+
Bartonella henselae	YP_033595.1	Full length	DNA topoisomerase IV subunit B	Insoluble	+	−
Bartonella henselae	YP_033416.1	Full length	Hypothetical protein	Insoluble	++	−
Borrelia burgdorferi	NP_212600.1	Full length	Holliday junction DNA helicase B	No expression	++	++
Brucella melitensis	YP_419002	Full length	Catalase	Insoluble	++	+
Brucella melitensis	YP_419049	Full length	ATP/GTP-binding site motif A (P-loop):ABC transporter:AAA ATPase:TOBE domain	Insoluble	ND	ND
Brucella melitensis	YP_414617	Full length	ATP/GTP-binding site motif A (P-loop):ABC transporter:AAA ATPase:TOBE domain	No expression	++	++
Brucella melitensis	YP_414349	Full length	Acetyl-CoA carboxylase, biotin carboxylase:carbamoyl-phosphate synthase L chain, ATP-binding:carbamoyl-phosphate synthetase l	No expression	++	+
Brucella melitensis	YP_419065	Full length	Blue (type 1) copper domain:blue (type 1) copper protein:amicyanin:plastocyanin	No expression	+	−
Brucella melitensis	YP_419020	Full length	Glutamate decarboxylase α	Insoluble	+	−
Brucella melitensis	YP_415432	Full length	Thioredoxin:thioredoxin type domain:thioredoxin domain 2	Soluble	++	ND
Burkholderia pseudomallei	YP_333769	Full length	Thioredoxin 1	Soluble	++	++
Burkholderia pseudomallei	YP_334416.1	Full length	Chorismate mutase	No expression	++	++
Burkholderia pseudomallei	ZP_04891863.1	267–404	Hemagglutinin-family protein	Insoluble	++	++
Burkholderia pseudomallei	YP_331616.1	Full length	Branched-chain amino-acid ABC transporter, ATP-binding protein	Insoluble	++	+++
Burkholderia pseudomallei	YP_334791.1	Full length	30S ribosomal protein S9	No expression	−	−
Burkholderia pseudomallei	YP_334870	Full length	3-Dehydroquinate dehydratase	Insoluble	+	+++
Burkholderia pseudomallei	YP_332852	Full length	NADH dehydrogenase subunit I	Insoluble	+	+++
Burkholderia pseudomallei	YP_334097	Full length	Phosphopyruvate hydratase	Insoluble	+	ND
Burkholderia pseudomallei	ABA48070.1	Bp 90–510	Sensor histidine kinase	Insoluble	++	++
Burkholderia pseudomallei	YP_333873	Full length	ATP-dependent protease ATP-binding subunit	No expression	+	−
Burkholderia pseudomallei	YP_334398.2	Full length	Adenosine deaminase	Soluble	+++	ND
Burkholderia pseudomallei	YP_334535.1	Full length	dTDP-glucose 4,6-dehydratase	Soluble	++	ND
Burkholderia pseudomallei	YP_333748	Full length	Histidyl-tRNA synthetase	Soluble	−	−
Ehrlichia ruminantium	YP_196632.1	Bp 96–891	FAD-dependent thymidylate synthase	ND	+	++
Ehrlichia ruminantium	YP_196632.1	Bp 96–762	FAD-dependent thymidylate synthase	ND	+	++
Ehrlichia ruminantium	YP_196632.1	Bp 96–654	FAD-dependent thymidylate synthase	ND	++	+
Leishmania infantum	XP_001464664.1	Full length	Elongation factor 1α	Insoluble	+	−
Mycobacterium tuberculosis	NP_216165.1	Full length	Phenylalanyl-tRNA synthetase subunit α	Insoluble	+++	+
Mycobacterium tuberculosis	NP_216786.1	Bp 57–525	Lipoprotein lppN	ND	++	+++
Mycobacterium tuberculosis	NP_217463.1	Full length	Probable polyketide synthase PKS15	No expression	++	++
Rickettsia conorii	NP_360910.1	Bp 3219–4419	190 kDa cell-surface antigen	Insoluble	+++	++
Rickettsia prowazekii	AAF34121.1	Bp 1–1095	OmpB	Insoluble	++	+
Rickettsia prowazekii	NP_221145	Full length	NADH dehydrogenase subunit I	Insoluble	ND	ND
Rickettsia rickettsii	P15921.1	3900–4953	Outer membrane protein A	Insoluble	++	+++
Rickettsia rickettsii	YP_001650445.1	Full length	Outer membrane protein B	ND	++	+
Rickettsia rickettsii	AAQ82709.1	3900–4953	Outer membrane protein A	ND	+	+
Trypanosoma brucei	XP_822456.1	Full length	Hexokinase	Insoluble	+	−