title: Pair-wise interactions of polymerization inhibitory contact site mutations of hemoglobin-S.
abstract: The linkage of pair-wise interactions of contact site mutations of HbS has been studied using Le Lamentin [His-20 (alpha)-->Gln], Hoshida [Glu-43 (beta)-->Gln] and alpha(2)beta (2) (T87Q) mutations as the prototype of three distinct classes of contact sites of deoxy HbS fiber. Binary mixture experiments established that beta(A)-chain with the Thr-87 (beta)-->Gln mutation is as potent as the gamma-chain of HbF (alpha(2)gamma(2)) in inhibiting polymerization. On combining the influence of Le Lamentin mutation with that of beta (2) (T87Q) mutations; the net influence is only partial additivity. On the other hand, in binary mixture studies, combined influence of Hoshida mutation with that of beta (2) (T87Q) mutations is synergistic. Besides, a significant level of synergistic complementation is also seen when the Le Lamentin and Hoshida mutations are combined in HbS (symmetrical tetramers). Le Lamentin and Hoshida mutation introduced into the cis-dimer of the asymmetric hybrid tetramer completely neutralizes the Val-6 (beta) dependent polymerization. Accordingly, we propose that combining the perturbation of intra-double strand contact site with that of an inter-double strand contact site exhibit synergy when they are present in two different chains of the alphabeta dimer. A comparison of the present results with that of the earlier studies suggest that when the two contact site perturbations are from the same sub-unit of the alphabeta dimer only partial additivity is observed. The map of interaction linkage of the contact site mutations exposes new strategies in the design of novel anti-sickling Hbs for the gene therapy of sickle cell disease.
authors.affiliation: Division of Hematology Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York, 10461, USA.
authors.forename: Sonati
authors.initials: S
authors.lastname: Srinivasulu
authors.forename: Krishnaveni
authors.initials: K
authors.lastname: Perumalsamy
authors.forename: Rajendra
authors.initials: R
authors.lastname: Upadhya
authors.forename: Belur N
authors.initials: BN
authors.lastname: Manjula
authors.forename: Steven
authors.initials: S
authors.lastname: Feiring
authors.forename: Raouf
authors.initials: R
authors.lastname: Alami
authors.forename: Eric
authors.initials: E
authors.lastname: Bouhassira
authors.forename: Mary E
authors.initials: ME
authors.lastname: Fabry
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Nagel
authors.forename: A Seetharama
authors.initials: AS
authors.lastname: Acharya
mesh_terms: D000818:Animals; D001704:Biopolymers; D006451:Hemoglobin, Sickle / Q000737:chemistry* / Q000235:genetics; D006455:Hemoglobins, Abnormal / Q000737:chemistry / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation
chemical_list: D001704:Biopolymers; D006451:Hemoglobin, Sickle; D006455:Hemoglobins, Abnormal; C074595:hemoglobin Hoshida; C035852:hemoglobin Le Lamentin