(b).

Oligonucleotide primers. Restriction sites are underlined. /5phos/ represents phosphorylation at the 5-end.

Primer	Oligonucleotide sequence 5 to 3	Restriction sites/mutation
SpsB_F1	AAAGGCGCCAAATTTATTGTTACGCCATATACAAT	KasI
SpsB_R1	AAAGAATTCTTAATTTTTAGTATTTTCAGGATTGAA	EcoRI
S36A_F2	/5phos/GCAATGGATCCAACTTTGAAAGATG	S36A
S36A_R2	/5phos/TTCACCTTTAATTGTATATGGCGTA
MBPpProEx_F6	/5phos/ATGAATCCCGGGCCAACGACCGAAAACCTGTATTTTCAG	SmaI
MBPpProEx_R6	/5phos/ATGCATATGGTGATGGTGATGGTGATGGTAGTA	NdeI
MBP_F7	GTAAACATATGCTGGTAATCTGGATTAACGGCG	NdeI
MBP_R7	GTAAACCCGGGATTAGTCTGCGCGTCTTTCAGG	SmaI
MBPLink_F8	/5phos/GCCATTGTTACGCCATATAGAA
MBPLink3_R8	/5phos/GCCCGCATTAGTCTGCGCGTCT	AGA linker
MBPLink4_R9	/5phos/GCCACCCGCATTAGTCTGCGCG	AGGA linker
MBPLink5_R10	/5phos/GCCAGAACCCGCATTAGTCTGC	AGSGA linker
GFP_F11	AAACCATGGTGAGCAAGGGCGAGGAGCTG	NcoI
GFP_R11	AAAGCGGCCGCTTTACTTGTACAGCTCATCTACG	NotI

^†Crystallized construct.